<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def register_command(self, name, command):
 """ Registers the `command` with the given `name`. If the `name` has already been used to register a command a :exc:`RuntimeError` will be raised. """

        if name in self.commands:
            raise RuntimeError('%s is already defined' % name)
        self.commands[name] = command