def add_process(self, command=None, vsplit=False, start_directory=None):
assert command is None or isinstance(command, six.text_type)<EOL>assert start_directory is None or isinstance(start_directory, six.text_type)<EOL>window = self.arrangement.get_active_window()<EOL>pane = self._create_pane(window, command, start_directory=start_directory)<EOL>window.add_pane(pane, vsplit=vsplit)<EOL>pane.focus()<EOL>self.invalidate()<EOL>
Add a new process to the current window. (vsplit/hsplit).