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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _check_series_convert_timestamps_internal(s, timezone):
 """ Convert a tz-naive timestamp in the specified timezone or local timezone to UTC normalized for Spark internal storage :param s: a pandas.Series :param timezone: the timezone to convert. if None then use local timezone :return pandas.Series where if it is a timestamp, has been UTC normalized without a time zone """

    from pyspark.sql.utils import require_minimum_pandas_version
    require_minimum_pandas_version()

    from pandas.api.types import is_datetime64_dtype, is_datetime64tz_dtype
    # TODO: handle nested timestamps, such as ArrayType(TimestampType())?
    if is_datetime64_dtype(s.dtype):
        # When tz_localize a tz-naive timestamp, the result is ambiguous if the tz-naive
        # timestamp is during the hour when the clock is adjusted backward during due to
        # daylight saving time (dst).
        # E.g., for America/New_York, the clock is adjusted backward on 2015-11-01 2:00 to
        # 2015-11-01 1:00 from dst-time to standard time, and therefore, when tz_localize
        # a tz-naive timestamp 2015-11-01 1:30 with America/New_York timezone, it can be either
        # dst time (2015-01-01 1:30-0400) or standard time (2015-11-01 1:30-0500).
        #
        # Here we explicit choose to use standard time. This matches the default behavior of
        # pytz.
        #
        # Here are some code to help understand this behavior:
        # >>> import datetime
        # >>> import pandas as pd
        # >>> import pytz
        # >>>
        # >>> t = datetime.datetime(2015, 11, 1, 1, 30)
        # >>> ts = pd.Series([t])
        # >>> tz = pytz.timezone('America/New_York')
        # >>>
        # >>> ts.dt.tz_localize(tz, ambiguous=True)
        # 0   2015-11-01 01:30:00-04:00
        # dtype: datetime64[ns, America/New_York]
        # >>>
        # >>> ts.dt.tz_localize(tz, ambiguous=False)
        # 0   2015-11-01 01:30:00-05:00
        # dtype: datetime64[ns, America/New_York]
        # >>>
        # >>> str(tz.localize(t))
        # '2015-11-01 01:30:00-05:00'
        tz = timezone or _get_local_timezone()
        return s.dt.tz_localize(tz, ambiguous=False).dt.tz_convert('UTC')
    elif is_datetime64tz_dtype(s.dtype):
        return s.dt.tz_convert('UTC')
    else:
        return s