Make DateOffset.kwds a property
Returning to an older goal of making DateOffset immutable, this PR moves towards getting rid of `DateOffset.kwds` by making it a property instead of regular attribute.  This uses the `_get_attributes_dict` pattern, albeit without actually using a `_get_attributes_dict` method.

I expect this to entail a small perf penalty since lookups are slower, but that's small potatoes next to the speedups we'll get from caching once these are immutable.


```
asv continuous -E virtualenv -f 1.1 master HEAD -b offset -b timeseries
[...]
    before     after       ratio
  [d3f7d2a6] [fe7a7187]
+   11.46μs    41.89μs      3.66  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<DateOffset: kwds={'months': 2, 'days': 2}>)
+    2.03ms     5.53ms      2.72  timeseries.ResampleSeries.time_resample('datetime', '5min', 'mean')
+    2.15ms     4.68ms      2.17  timeseries.ResampleSeries.time_resample('datetime', '1D', 'ohlc')
+   14.36μs    29.72μs      2.07  offset.OffestDatetimeArithmetic.time_add_10(<YearEnd: month=12>)
+    2.56ms     4.42ms      1.73  timeseries.ToDatetimeCache.time_dup_string_tzoffset_dates(True)
+   11.83μs    18.85μs      1.59  offset.OffestDatetimeArithmetic.time_add(<DateOffset: kwds={'months': 2, 'days': 2}>)
+    9.60μs    14.96μs      1.56  offset.OffestDatetimeArithmetic.time_apply(<DateOffset: kwds={'months': 2, 'days': 2}>)
+   28.55μs    42.49μs      1.49  offset.OffestDatetimeArithmetic.time_subtract(<DateOffset: kwds={'months': 2, 'days': 2}>)
+   12.76μs    18.56μs      1.45  offset.OffestDatetimeArithmetic.time_add(<BusinessYearEnd: month=12>)
+    7.69μs    10.75μs      1.40  timeseries.AsOf.time_asof_single_early('Series')
+    8.71ms    11.63ms      1.34  timeseries.ResampleSeries.time_resample('period', '5min', 'mean')
+   15.21μs    20.20μs      1.33  offset.OffestDatetimeArithmetic.time_add_10(<MonthEnd>)
+   14.20μs    18.47μs      1.30  offset.OffestDatetimeArithmetic.time_add_10(<BusinessQuarterEnd: startingMonth=3>)
+   17.44μs    21.72μs      1.25  offset.OffestDatetimeArithmetic.time_subtract_10(<SemiMonthBegin: day_of_month=15>)
+   11.22μs    13.54μs      1.21  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<YearEnd: month=12>)
+   13.63μs    16.37μs      1.20  offset.OffestDatetimeArithmetic.time_subtract(<BusinessMonthBegin>)
+   10.22μs    12.27μs      1.20  offset.OffestDatetimeArithmetic.time_apply(<BusinessDay>)
+   65.62μs    78.64μs      1.20  offset.OffestDatetimeArithmetic.time_add_10(<DateOffset: kwds={'months': 2, 'days': 2}>)
+   14.46μs    17.28μs      1.19  offset.OffestDatetimeArithmetic.time_subtract(<QuarterBegin: startingMonth=3>)
+   16.11μs    19.14μs      1.19  offset.OffestDatetimeArithmetic.time_subtract(<BusinessDay>)
+   16.31μs    19.07μs      1.17  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessYearBegin: month=1>)
+    2.35ms     2.73ms      1.16  timeseries.DatetimeIndex.time_unique('tz_naive')
+   15.43μs    17.89μs      1.16  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessMonthBegin>)
+   10.68μs    12.38μs      1.16  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<MonthEnd>)
+   10.57μs    12.24μs      1.16  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessMonthEnd>)
+   14.26μs    16.48μs      1.16  offset.OffestDatetimeArithmetic.time_add_10(<MonthBegin>)
+  121.98μs   140.64μs      1.15  offset.OffestDatetimeArithmetic.time_subtract_10(<DateOffset: kwds={'months': 2, 'days': 2}>)
+   16.60μs    19.11μs      1.15  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessYearEnd: month=12>)
+   15.66μs    18.00μs      1.15  offset.OffestDatetimeArithmetic.time_subtract(<YearEnd: month=12>)
+   16.78μs    19.25μs      1.15  offset.OffestDatetimeArithmetic.time_subtract(<SemiMonthEnd: day_of_month=15>)
+   13.87μs    15.89μs      1.15  offset.OffestDatetimeArithmetic.time_add_10(<BusinessYearEnd: month=12>)
+   14.96μs    17.13μs      1.14  offset.OffestDatetimeArithmetic.time_subtract(<BusinessQuarterBegin: startingMonth=3>)
+   15.27μs    17.43μs      1.14  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessMonthEnd>)
+   12.88μs    14.66μs      1.14  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessDay>)
+  251.65μs   285.47μs      1.13  offset.OffsetDatetimeIndexArithmetic.time_add_offset(<BusinessQuarterEnd: startingMonth=3>)
+   13.84μs    15.66μs      1.13  offset.OffestDatetimeArithmetic.time_add_10(<YearBegin: month=1>)
+   14.68ms    16.59ms      1.13  timeseries.DatetimeIndex.time_to_time('tz_naive')
+   16.66μs    18.79μs      1.13  offset.OffestDatetimeArithmetic.time_subtract_10(<YearEnd: month=12>)
+   10.00μs    11.19μs      1.12  offset.OffestDatetimeArithmetic.time_apply(<BusinessYearBegin: month=1>)
+   10.30μs    11.50μs      1.12  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessYearEnd: month=12>)
+   17.44μs    19.47μs      1.12  offset.OffestDatetimeArithmetic.time_subtract(<SemiMonthBegin: day_of_month=15>)
+   18.07μs    20.13μs      1.11  offset.OffestDatetimeArithmetic.time_add_10(<SemiMonthEnd: day_of_month=15>)
+   18.09μs    20.08μs      1.11  offset.OffestDatetimeArithmetic.time_add(<CustomBusinessDay>)
+   14.65μs    16.26μs      1.11  offset.OffestDatetimeArithmetic.time_add_10(<BusinessMonthEnd>)
+    5.32ms     5.91ms      1.11  offset.OffsetDatetimeIndexArithmetic.time_add_offset(<SemiMonthBegin: day_of_month=15>)
+   11.54μs    12.80μs      1.11  offset.OffestDatetimeArithmetic.time_add(<MonthBegin>)
+   12.23μs    13.55μs      1.11  offset.OffestDatetimeArithmetic.time_add(<BusinessQuarterEnd: startingMonth=3>)
+   15.25μs    16.87μs      1.11  offset.OffestDatetimeArithmetic.time_subtract_10(<MonthEnd>)
+   17.78μs    19.66μs      1.11  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessDay>)
+   18.13μs    20.05μs      1.11  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessQuarterEnd: startingMonth=3>)
+   21.89μs    24.19μs      1.10  offset.OffestDatetimeArithmetic.time_subtract_10(<Day>)
+    9.94μs    10.97μs      1.10  offset.OffestDatetimeArithmetic.time_apply(<SemiMonthEnd: day_of_month=15>)
+   10.74μs    11.85μs      1.10  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessYearBegin: month=1>)
+   18.51μs    20.39μs      1.10  offset.OffestDatetimeArithmetic.time_subtract_10(<SemiMonthEnd: day_of_month=15>)
+   39.52ms    43.52ms      1.10  timeseries.Factorize.time_factorize('Asia/Tokyo')
-   16.22μs    14.75μs      0.91  offset.OffestDatetimeArithmetic.time_add_10(<QuarterBegin: startingMonth=3>)
-   73.13ms    65.36ms      0.89  timeseries.ToDatetimeCache.time_dup_string_tzoffset_dates(False)
-   13.39μs    11.60μs      0.87  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessQuarterBegin: startingMonth=3>)
-   25.04μs    21.37μs      0.85  offset.OffestDatetimeArithmetic.time_add_10(<Day>)
-   14.25μs    11.66μs      0.82  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<QuarterEnd: startingMonth=3>)
-   44.47ms    34.93ms      0.79  timeseries.Factorize.time_factorize(None)
-    1.98ms     1.45ms      0.73  timeseries.ToDatetimeCache.time_dup_string_dates(False)
-    4.23ms     1.69ms      0.40  timeseries.ResampleSeries.time_resample('datetime', '1D', 'mean')

asv continuous -E virtualenv -f 1.1 master HEAD -b offset -b timeseries
[...]
+   17.01μs    35.30μs      2.08  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessQuarterBegin: startingMonth=3>)
+    3.02ms     4.90ms      1.62  timeseries.AsOf.time_asof_nan_single('DataFrame')
+   77.45ms   124.97ms      1.61  timeseries.Factorize.time_factorize('Asia/Tokyo')
+   12.33μs    19.34μs      1.57  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<DateOffset: days=2, months=2>)
+    9.65μs    14.70μs      1.52  offset.OffestDatetimeArithmetic.time_apply(<DateOffset: days=2, months=2>)
+   11.65μs    17.30μs      1.48  offset.OffestDatetimeArithmetic.time_add(<DateOffset: days=2, months=2>)
+   27.81μs    40.60μs      1.46  offset.OffestDatetimeArithmetic.time_subtract(<DateOffset: days=2, months=2>)
+   71.60μs    91.28μs      1.27  offset.OffestDatetimeArithmetic.time_add(<CustomBusinessMonthEnd>)
+   92.47μs   113.39μs      1.23  offset.OffestDatetimeArithmetic.time_subtract(<CustomBusinessMonthBegin>)
+   18.89μs    23.02μs      1.22  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<Day>)
+   10.49μs    12.66μs      1.21  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessMonthBegin>)
+   16.88μs    20.14μs      1.19  offset.OffestDatetimeArithmetic.time_subtract(<SemiMonthEnd: day_of_month=15>)
+   15.45μs    18.27μs      1.18  offset.OffestDatetimeArithmetic.time_add_10(<QuarterEnd: startingMonth=3>)
+    8.37μs     9.90μs      1.18  offset.OffestDatetimeArithmetic.time_apply(<MonthBegin>)
+   62.24μs    73.22μs      1.18  offset.OffestDatetimeArithmetic.time_add_10(<DateOffset: days=2, months=2>)
+   21.38μs    24.98μs      1.17  offset.OffestDatetimeArithmetic.time_add_10(<Day>)
+   16.28μs    18.91μs      1.16  offset.OffestDatetimeArithmetic.time_subtract_10(<QuarterBegin: startingMonth=3>)
+   12.20μs    14.11μs      1.16  offset.OffestDatetimeArithmetic.time_add(<BusinessQuarterEnd: startingMonth=3>)
+   11.51μs    13.30μs      1.16  offset.OffestDatetimeArithmetic.time_add(<BusinessYearBegin: month=1>)
+   12.89μs    14.83μs      1.15  offset.OffestDatetimeArithmetic.time_add(<SemiMonthBegin: day_of_month=15>)
+   14.39μs    16.51μs      1.15  offset.OffestDatetimeArithmetic.time_add_10(<QuarterBegin: startingMonth=3>)
+   10.50μs    12.03μs      1.15  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<YearEnd: month=12>)
+    2.32ms     2.66ms      1.14  timeseries.DatetimeIndex.time_unique('tz_naive')
+   15.92μs    18.08μs      1.14  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessMonthEnd>)
+  123.41μs   140.13μs      1.14  offset.OffestDatetimeArithmetic.time_subtract_10(<DateOffset: days=2, months=2>)
+   71.20ms    80.52ms      1.13  offset.OffsetSeriesArithmetic.time_add_offset(<CustomBusinessMonthEnd>)
+   17.68μs    19.89μs      1.13  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessYearBegin: month=1>)
+   15.36μs    17.23μs      1.12  offset.OffestDatetimeArithmetic.time_subtract_10(<MonthBegin>)
+   15.98μs    17.82μs      1.12  offset.OffestDatetimeArithmetic.time_add_10(<SemiMonthBegin: day_of_month=15>)
+   14.64μs    16.31μs      1.11  offset.OffestDatetimeArithmetic.time_add_10(<BusinessMonthEnd>)
+    8.96μs     9.94μs      1.11  offset.OffestDatetimeArithmetic.time_apply(<BusinessYearEnd: month=12>)
+   17.27μs    19.16μs      1.11  offset.OffestDatetimeArithmetic.time_subtract_10(<YearEnd: month=12>)
+   14.44μs    16.01μs      1.11  offset.OffestDatetimeArithmetic.time_subtract(<BusinessYearBegin: month=1>)
+   15.26μs    16.90μs      1.11  offset.OffestDatetimeArithmetic.time_add_10(<BusinessDay>)
+   14.19μs    15.70μs      1.11  offset.OffestDatetimeArithmetic.time_subtract(<MonthBegin>)
+   13.72μs    15.16μs      1.11  offset.OffestDatetimeArithmetic.time_add_10(<MonthEnd>)
+  127.38μs   140.62μs      1.10  offset.OffestDatetimeArithmetic.time_add_10(<CustomBusinessMonthBegin>)
+   13.77μs    15.20μs      1.10  offset.OffestDatetimeArithmetic.time_subtract(<BusinessMonthEnd>)
-   17.66μs    15.89μs      0.90  offset.OffestDatetimeArithmetic.time_subtract_10(<MonthEnd>)
-    4.07ms     3.66ms      0.90  timeseries.ToDatetimeISO8601.time_iso8601_nosep
-   25.01μs    22.41μs      0.90  offset.OffestDatetimeArithmetic.time_subtract_10(<Day>)
-   11.44μs    10.22μs      0.89  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<MonthEnd>)
-   18.64μs    16.19μs      0.87  timeseries.AsOf.time_asof_single('Series')
-   92.96ms    77.71ms      0.84  timeseries.Factorize.time_factorize(None)
-   23.06μs    19.02μs      0.83  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessYearEnd: month=12>)
-   13.05μs    10.37μs      0.79  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<YearBegin: month=1>)
-   23.95μs    14.14μs      0.59  offset.OffestDatetimeArithmetic.time_add(<MonthBegin>)
-  444.49μs   260.00μs      0.58  offset.OffsetDatetimeIndexArithmetic.time_add_offset(<BusinessYearEnd: month=12>)
-    4.31ms     2.46ms      0.57  timeseries.ToDatetimeCache.time_unique_seconds_and_unit(False)
-   21.43μs    11.69μs      0.55  offset.OffestDatetimeArithmetic.time_apply(<BusinessDay>)

asv continuous -E virtualenv -f 1.1 master HEAD -b offset -b timeseries
[...]
    before     after       ratio
  [d3f7d2a6] [fe7a7187]
+   16.58μs    26.15μs      1.58  offset.OffestDatetimeArithmetic.time_subtract(<BusinessQuarterEnd: startingMonth=3>)
+    9.75μs    14.73μs      1.51  offset.OffestDatetimeArithmetic.time_apply(<DateOffset: days=2, months=2>)
+   12.16μs    18.11μs      1.49  offset.OffestDatetimeArithmetic.time_add(<DateOffset: days=2, months=2>)
+   12.21μs    17.69μs      1.45  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<DateOffset: days=2, months=2>)
+   28.97μs    40.89μs      1.41  offset.OffestDatetimeArithmetic.time_subtract(<DateOffset: days=2, months=2>)
+    1.63ms     2.25ms      1.38  timeseries.ResampleSeries.time_resample('datetime', '1D', 'mean')
+   14.71μs    20.02μs      1.36  offset.OffestDatetimeArithmetic.time_subtract(<BusinessYearBegin: month=1>)
+   14.63μs    19.70μs      1.35  offset.OffestDatetimeArithmetic.time_subtract(<BusinessMonthBegin>)
+   19.52μs    26.26μs      1.35  offset.OffestDatetimeArithmetic.time_add(<CustomBusinessDay>)
+   22.16ms    29.79ms      1.34  offset.OffsetSeriesArithmetic.time_add_offset(<CustomBusinessDay>)
+   20.69ms    26.91ms      1.30  timeseries.IrregularOps.time_add
+   16.77μs    20.77μs      1.24  offset.OffestDatetimeArithmetic.time_subtract(<SemiMonthEnd: day_of_month=15>)
+   15.76μs    19.40μs      1.23  offset.OffestDatetimeArithmetic.time_subtract_10(<MonthBegin>)
+   17.31μs    21.15μs      1.22  offset.OffestDatetimeArithmetic.time_subtract_10(<QuarterBegin: startingMonth=3>)
+   15.31μs    18.65μs      1.22  offset.OffestDatetimeArithmetic.time_subtract(<BusinessQuarterBegin: startingMonth=3>)
+   14.71μs    17.75μs      1.21  offset.OffestDatetimeArithmetic.time_add_10(<YearBegin: month=1>)
+   15.88μs    19.10μs      1.20  offset.OffestDatetimeArithmetic.time_subtract(<BusinessDay>)
+    6.38ms     7.55ms      1.18  timeseries.AsOf.time_asof('DataFrame')
+   16.25μs    18.97μs      1.17  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessQuarterEnd: startingMonth=3>)
+   66.50μs    76.79μs      1.15  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<CustomBusinessMonthEnd>)
+   19.02μs    21.70μs      1.14  offset.OffestDatetimeArithmetic.time_add(<Day>)
+   13.95μs    15.83μs      1.13  offset.OffestDatetimeArithmetic.time_subtract(<MonthEnd>)
+   18.43μs    20.88μs      1.13  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<Day>)
+   64.88μs    72.92μs      1.12  offset.OffestDatetimeArithmetic.time_add_10(<DateOffset: days=2, months=2>)
+   12.91μs    14.43μs      1.12  offset.OffestDatetimeArithmetic.time_add(<QuarterEnd: startingMonth=3>)
+   15.23μs    16.99μs      1.12  offset.OffestDatetimeArithmetic.time_add_10(<BusinessDay>)
+   13.70μs    15.24μs      1.11  offset.OffestDatetimeArithmetic.time_add_10(<YearEnd: month=12>)
+  131.58μs   145.99μs      1.11  offset.OffestDatetimeArithmetic.time_subtract_10(<DateOffset: days=2, months=2>)
+   11.07μs    12.26μs      1.11  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessQuarterBegin: startingMonth=3>)
+   11.14μs    12.34μs      1.11  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<MonthBegin>)
+   11.60μs    12.84μs      1.11  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessMonthEnd>)
+    2.44ms     2.70ms      1.11  timeseries.DatetimeIndex.time_unique('tz_naive')
+   15.79μs    17.46μs      1.11  offset.OffestDatetimeArithmetic.time_subtract_10(<BusinessMonthEnd>)
+   21.47μs    23.70μs      1.10  offset.OffestDatetimeArithmetic.time_subtract(<Day>)
+   10.57μs    11.64μs      1.10  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessMonthBegin>)
+    2.98μs     3.28μs      1.10  timeseries.DatetimeIndex.time_get('repeated')
-   10.04μs     9.07μs      0.90  offset.OffestDatetimeArithmetic.time_apply(<BusinessMonthBegin>)
-   12.54μs    11.29μs      0.90  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<YearEnd: month=12>)
-   10.30μs     9.25μs      0.90  offset.OffestDatetimeArithmetic.time_apply(<QuarterBegin: startingMonth=3>)
-   16.50μs    14.67μs      0.89  offset.OffestDatetimeArithmetic.time_add_10(<QuarterEnd: startingMonth=3>)
-    8.11ms     6.98ms      0.86  timeseries.Factorize.time_factorize(None)
-    7.85ms     6.72ms      0.86  timeseries.Factorize.time_factorize('Asia/Tokyo')
-   20.75μs    13.16μs      0.63  offset.OffestDatetimeArithmetic.time_add(<MonthEnd>)
-    2.00ms     1.21ms      0.60  timeseries.ResampleDataFrame.time_method('mean')
-    3.99ms     2.34ms      0.59  timeseries.ToDatetimeCache.time_dup_string_dates(True)
-   19.81μs    11.38μs      0.57  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<BusinessYearBegin: month=1>)
-   30.71μs    12.91μs      0.42  offset.OffestDatetimeArithmetic.time_add(<BusinessQuarterEnd: startingMonth=3>)

asv continuous -E virtualenv -f 1.1 master HEAD -b offset -b timeseries
[...]
    before     after       ratio
  [d3f7d2a6] [fe7a7187]
+   13.89μs    26.44μs      1.90  offset.OffestDatetimeArithmetic.time_add(<BusinessMonthEnd>)
+    9.67μs    15.55μs      1.61  offset.OffestDatetimeArithmetic.time_apply(<DateOffset: days=2, months=2>)
+   11.64μs    17.55μs      1.51  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<DateOffset: days=2, months=2>)
+   12.28μs    17.62μs      1.43  offset.OffestDatetimeArithmetic.time_add(<DateOffset: days=2, months=2>)
+   30.04μs    40.47μs      1.35  offset.OffestDatetimeArithmetic.time_subtract(<DateOffset: days=2, months=2>)
+   14.31μs    17.84μs      1.25  offset.OffestDatetimeArithmetic.time_subtract(<YearBegin: month=1>)
+   14.24μs    17.55μs      1.23  offset.OffestDatetimeArithmetic.time_add_10(<QuarterBegin: startingMonth=3>)
+   16.80μs    20.62μs      1.23  offset.OffestDatetimeArithmetic.time_add_10(<SemiMonthEnd: day_of_month=15>)
+   15.42μs    18.40μs      1.19  offset.OffestDatetimeArithmetic.time_subtract_10(<MonthBegin>)
+   61.16μs    72.26μs      1.18  offset.OffestDatetimeArithmetic.time_add_10(<DateOffset: days=2, months=2>)
+   14.30μs    16.82μs      1.18  offset.OffestDatetimeArithmetic.time_add_10(<BusinessQuarterEnd: startingMonth=3>)
+   14.67μs    17.24μs      1.18  offset.OffestDatetimeArithmetic.time_add_10(<QuarterEnd: startingMonth=3>)
+    9.54μs    11.21μs      1.17  offset.OffestDatetimeArithmetic.time_apply(<QuarterEnd: startingMonth=3>)
+   17.11μs    20.00μs      1.17  offset.OffestDatetimeArithmetic.time_subtract_10(<QuarterBegin: startingMonth=3>)
+   15.54μs    18.01μs      1.16  offset.OffestDatetimeArithmetic.time_apply(<CustomBusinessDay>)
+   10.34μs    11.95μs      1.16  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<MonthEnd>)
+  123.20μs   141.04μs      1.14  offset.OffestDatetimeArithmetic.time_subtract_10(<DateOffset: days=2, months=2>)
+   13.93μs    15.85μs      1.14  offset.OffestDatetimeArithmetic.time_add_10(<YearBegin: month=1>)
+   11.39μs    12.85μs      1.13  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<YearEnd: month=12>)
+   16.79μs    18.84μs      1.12  offset.OffestDatetimeArithmetic.time_subtract_10(<QuarterEnd: startingMonth=3>)
+    2.35ms     2.64ms      1.12  timeseries.DatetimeIndex.time_unique('tz_naive')
+    4.16μs     4.67μs      1.12  timeseries.DatetimeIndex.time_get('dst')
+    6.03μs     6.73μs      1.12  timeseries.DatetimeIndex.time_get('tz_aware')
+   16.77μs    18.74μs      1.12  offset.OffestDatetimeArithmetic.time_add_10(<BusinessDay>)
+   10.47μs    11.69μs      1.12  offset.OffestDatetimeArithmetic.time_apply(<BusinessDay>)
+   12.36μs    13.67μs      1.11  offset.OffestDatetimeArithmetic.time_add(<YearBegin: month=1>)
+    9.49μs    10.49μs      1.11  offset.OffestDatetimeArithmetic.time_apply(<BusinessQuarterEnd: startingMonth=3>)
+  105.28μs   116.31μs      1.10  offset.OffestDatetimeArithmetic.time_apply(<CustomBusinessMonthBegin>)
+   18.86μs    20.84μs      1.10  offset.OffestDatetimeArithmetic.time_subtract_10(<SemiMonthEnd: day_of_month=15>)
+   14.58μs    16.07μs      1.10  offset.OffestDatetimeArithmetic.time_subtract(<MonthBegin>)
-    4.33ms     3.93ms      0.91  offset.OnOffset.time_on_offset(<CustomBusinessMonthBegin>)
-    2.30ms     2.05ms      0.89  timeseries.ResampleSeries.time_resample('datetime', '1D', 'ohlc')
-  148.28ms   131.47ms      0.89  timeseries.DatetimeIndex.time_to_pydatetime('tz_aware')
-   10.14μs     8.93μs      0.88  offset.OffestDatetimeArithmetic.time_apply(<MonthEnd>)
-   13.64μs    11.91μs      0.87  offset.OffestDatetimeArithmetic.time_apply_np_dt64(<SemiMonthBegin: day_of_month=15>)
-   32.12μs    27.72μs      0.86  offset.OffestDatetimeArithmetic.time_add_10(<CustomBusinessDay>)
-   16.82μs    13.94μs      0.83  offset.OffestDatetimeArithmetic.time_add_10(<MonthEnd>)
-    3.27μs     2.59μs      0.79  timeseries.DatetimeIndex.time_get('repeated')
-  313.89μs   235.57μs      0.75  offset.OffsetDatetimeIndexArithmetic.time_add_offset(<QuarterEnd: startingMonth=3>)
-   23.48μs    15.20μs      0.65  offset.OffestDatetimeArithmetic.time_add(<BusinessYearEnd: month=12>)
-    3.96ms     2.55ms      0.64  timeseries.ResampleSeries.time_resample('period', '5min', 'ohlc')
-   23.80μs    13.81μs      0.58  offset.OffestDatetimeArithmetic.time_add(<BusinessDay>)
-    3.13ms     1.45ms      0.46  timeseries.ToDatetimeCache.time_dup_string_dates(False)
```


# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19403?src=pr&el=h1) Report
> Merging [#19403](https://codecov.io/gh/pandas-dev/pandas/pull/19403?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/35812eaaecebeeee0ddf07dee4b583c4eea07785?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/19403/graphs/tree.svg?token=eZ4WkYLtcO&width=650&src=pr&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/19403?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #19403      +/-   ##
==========================================
- Coverage   91.67%   91.67%   -0.01%     
==========================================
  Files         148      148              
  Lines       48553    48554       +1     
==========================================
  Hits        44513    44513              
- Misses       4040     4041       +1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.04% <100%> (-0.01%)` | :arrow_down: |
| #single | `41.71% <70%> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/19403?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/tseries/offsets.py](https://codecov.io/gh/pandas-dev/pandas/pull/19403/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvb2Zmc2V0cy5weQ==) | `97% <100%> (-0.09%)` | :arrow_down: |
| [pandas/core/indexes/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/19403/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9kYXRldGltZXMucHk=) | `95.25% <100%> (+0.01%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19403?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/19403?src=pr&el=footer). Last update [35812ea...53c251f](https://codecov.io/gh/pandas-dev/pandas/pull/19403?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 >did the repr change break anything? can you add some tests for this (doesn't have to be comprehensive, but some basic ones is ok)

Well it broke that one test.  Did you have something else in mind? looks fine. can you rebase and ping on green (just to make sure) ping thanks!