def METHOD_NAME(agent, ontology, ns_filter=None):
    """Return children agents of a given parent agent.
    Parameters
    ----------
    agent : indra.statements.Agent
        An INDRA Agent whose children in the given ontology should
        be returned as Agents.
    ontology : indra.ontology.IndraOntology
        An IndraOntology instance to use when finding the given Agent's
        children,
    ns_filter : Optional[set]
        If provided, only children Agents within the set of given
        name spaces are returned.
    Returns
    -------
    list of Agent
        A list of child INDRA Agents.
    """
    if agent is None:
        return []
    agns, agid = agent.get_grounding()
    if agns is None or agid is None:
        return []
    children = ontology.get_children(agns, agid, ns_filter=ns_filter)
    children_agents = [_agent_from_ns_id(*child) for child in children]
    return sorted(children_agents, key=lambda a: a.name)