'Print the help to the caller.
Args:
file (file-object): not used here, the caller is used.
Note:
This method will override `argparse.ArgumentParser`\'s in order
to not display the help on stdout or stderr, but to the
command\'s caller.'

def print_help(self, file=None):

    if self.command:
        self.command.msg(self.format_help().strip())
