def add_initiators_to_initiator_group(
        client,
        tag,
        initiators=None,
        netmasks=None):
    """Add initiators to an existing initiator group.

    Args:
        tag: Initiator group tag (unique, integer > 0)
        initiators: List of initiator hostnames or IP addresses, e.g. ["127.0.0.1","192.168.200.100"]
        netmasks: List of initiator netmasks, e.g. ["255.255.0.0","255.248.0.0"]

    Returns:
        True or False
    """
    params = {'tag': tag}

    if initiators:
        params['initiators'] = initiators
    if netmasks:
        params['netmasks'] = netmasks
    return client.call('add_initiators_to_initiator_group', params)