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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 value_occurence(s):
 """Count the number of times each value occurs. This function returns the counts for each row, in contrast with `pandas.value_counts <http://pandas.pydata.org/pandas- docs/stable/generated/pandas.Series.value_counts.html>`_. Returns ------- pandas.Series A Series with value counts. """


    # https://github.com/pydata/pandas/issues/3729
    value_count = s.fillna('NAN')

    return value_count.groupby(by=value_count).transform('count')