def initialize_agent
      return nil unless valid_rdf_subject?
      DPLA::MAP::Agent.new(rdf_subject).tap { |agent| agent.label = name }
    end
def initialize_agent
      return nil unless valid_rdf_subject?
      DPLA::MAP::Agent.new(rdf_subject).tap { |agent| agent.label = name }
    end
Creates DPLA::MAP::Agent object from the :rdf_subject and :name, ignoring
 bnodes.

 @return [DPLA::MAP::Agent]