# later operate on a Path type which represents an already parsed type.

# abc.def -> Just(def)
# abc. -> Just()  <- is this correct.
# .abc -> None  <- trims preceeding dots...
fn extension (path StrView) -> Maybe StrView
	path = path StrView.drop-while(fn c: c == '.')
	i = path.contents.count
	while i > 0
		i <= i - 1
		if path.contents[i] == '.' Char.ascii-u8()
			break
	
	# no extension
	if i == 0
		return None
	
	ext = path StrView.byte-substr(i + 1, path.contents.count)
	return Just(ext)