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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 _numeric_summary(arg, exact_nunique=False, prefix=None):
 """ Compute a set of summary metrics from the input numeric value expression Parameters arg : numeric value expression exact_nunique : boolean, default False prefix : string, default None String prefix for metric names Returns ------- summary : (count, # nulls, min, max, sum, mean, nunique) """

    metrics = [
        arg.count(),
        arg.isnull().sum().name('nulls'),
        arg.min(),
        arg.max(),
        arg.sum(),
        arg.mean(),
    ]

    if exact_nunique:
        unique_metric = arg.nunique().name('nunique')
    else:
        unique_metric = arg.approx_nunique().name('approx_nunique')

    metrics.append(unique_metric)
    return _wrap_summary_metrics(metrics, prefix)