def mean(data_list):
    """
    Accepts a sample of values and returns their mean.

    The mean is the sum of all values in the sample divided by
    the number of members. It is also known as the average.

    Since the value is strongly influenced by outliers, median
    is generally a better indicator of central tendency.

    h3. Example usage

        >> import calculate
        >> calculate.mean([1,2,3])
        2.0
        >> calculate.mean([1, 99])
        50.0

    h3. Documentation

        "mean":http://en.wikipedia.org/wiki/Arithmetic_mean
    """
    try:
        data_list = list(map(float, data_list))
    except ValueError:
        raise ValueError('Input values should contain numbers')
    n = len(data_list)
    sum_ = sum(data_list)
    return sum_ / n
