Get the selected topic by which this object has been defined.
See also
Other data selection functions:
as_acs_5yr_topic(),
get_available_area_topics(),
get_available_area_years(),
get_available_areas(),
get_geo_attribute_names(),
get_geo_layer.acs_5yr_geo(),
get_names_of_other_topics(),
get_report_names(),
get_subreport_names(),
select_report(),
select_subreport(),
select_topic()
