def apim_api_list(client, resource_group_name, service_name, filter_display_name=None, top=None, skip=None):
    """List all APIs of an API Management instance. """

    if filter_display_name is not None:
        filter_display_name = "properties/displayName eq '%s'" % filter_display_name

    return client.api.list_by_service(resource_group_name, service_name, filter=filter_display_name, skip=skip, top=top)