<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:

def slaves(self):
        '''The list of slave managers of this manager, if any.

        This information can also be found by listing the children of this node
        that are of type @ref Manager.

        '''
        with self._mutex:
            if not self._slaves:
                self._slaves = [c for c in self.children if c.is_manager]
        return self._slaves