code: def _agent_is_gene(agent, specific_only):
      
      if not specific_only:
          if not(agent.db_refs.get('HGNC') or \
                 agent.db_refs.get('UP') or \
                 agent.db_refs.get('FPLX')):
              return False
      else:
          if not(agent.db_refs.get('HGNC') or \
                 agent.db_refs.get('UP')):
              return False
      return True
docs: Returns whether an agent is for a gene.
  
      Parameters
      ----------
      agent: Agent
          The agent to evaluate
      specific_only : Optional[bool]
          If True, only elementary genes/proteins evaluate as genes and families
          will be filtered out. If False, families are also included.
  
      Returns
      -------
      is_gene: bool
          Whether the agent is a gene