<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def extend(self, *bindings):
 """ Append the given bindings to this keymap. Arguments: *bindings (Binding):
 Bindings to be added. Returns: Keymap: self """

        self._bindings.extend(self._preprocess(bindings))
        return self