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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 _mean_of_runs(stats, key='runs'):
 """Obtain the mean of stats. Args: stats: dict; A set of stats, structured as above. key: str; Optional key to determine where list of runs is found in stats """


    num_runs = len(stats[key])
    first = stats[key][0]

    mean = {}
    for stat_key in first:
        # Skip non numberic attributes
        if isinstance(first[stat_key], numbers.Number):
            mean[stat_key] = sum(run[stat_key]
                                 for run in stats[key]) / float(num_runs)

    return mean