def oxcom(lst):
    """Returns gramatical comma separated string of *lst*."""
    lst = [str(l) for l in lst]

    if not lst:
        return ''
    elif len(lst) == 1:
        return lst[0]
    elif len(lst) == 2:
        return ' and '.join(lst)
    else:
        return ', and '.join([', '.join(lst[:-1]), lst[-1]])