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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 first(series, order_by=None):
 """ Returns the first value of a series. Args: series (pandas.Series):
 column to summarize. Kwargs: order_by: a pandas.Series or list of series (can be symbolic) to order the input series by before summarization. """


    if order_by is not None:
        series = order_series_by(series, order_by)
    first_s = series.iloc[0]
    return first_s