Consider this code snippet, simplified from a real application:

def display(self, *columns)
    getter = attrgetter(*columns)
    toprint = [[str(x) for x in getter(row)] for row in self._rows]

This works great...as long as there are two or more columns to print.
If there is only one column, it bombs because the getter returns a value
instead of a tuple.

This would not be a problem in and of itself, but there is no way to
tell attrgetter that I want a tuple even if there is only one value.

I believe it would be backward compatible to allow:

    attrgetter(['a'])
    itemgetter(['a', 'b'])

to return a tuple, since a list cannot be an attribute name.  The same
would apply to itemgetter, since a list cannot be a dictionary key.