The docs for statistics.mean say, "Return the sample arithmetic mean of data, a sequence or iterator of real-valued numbers." Most of the functions in statistics have a `data` argument, but this function is the only one that says, "a sequence or iterator." The examples all show lists. The page would be better if the introduction mentioned what `data` could be, instead of having to guess that median can take an iterator because mean says that it can.
Updated patch based on feedback. Steven, I removed the example of median_grouped using Fractions. Would you be able to suggest better examples to be added in the docs? I also noticed that there are more examples of median_grouped in the paragraph below. Thanks.
