def reverse(self, col):
if col in self.options:<EOL><INDENT>if self.is_selected(col):<EOL><INDENT>return col if not self.asc else '<STR_LIT>'.format(col)<EOL><DEDENT>else:<EOL><INDENT>return col<EOL><DEDENT><DEDENT>return None<EOL>
Get reverse direction of ordering.