_:vb50911268	<http://www.w3.org/ns/r2rml#constant>	<http://xmlns.com/foaf/0.1/firstName> .
_:vb50911269	<http://www.w3.org/ns/r2rml#objectMap>	_:vb50911270 .
_:vb50911269	<http://www.w3.org/ns/r2rml#predicateMap>	_:vb50911268 .
_:vb50911270	<http://www.w3.org/ns/r2rml#column>	"first_name" .