def split(p):
"""Split a pathname. Returns tuple "(head, tail)" where "tail" is
everything after the final slash. Either part may be empty."""
p = os.fspath(p)
sep = _get_sep(p)
i = p.rfind(sep) + 1
head, tail = p[:i], p[i:]
if head and head != sep*len(head):
head = head.rstrip(sep)
return head, tail