@property<EOL><INDENT>def root_parent(self):<DEDENT>
if not self.parent:<EOL><INDENT>return None<EOL><DEDENT>return self.parents[-<NUM_LIT:1>]<EOL>
Retrieves the root parent of this command.

        If the command has no parents then it returns ``None``.

        For example in commands ``?a b c test``, the root parent is ``a``.