new_contents: import unittest
  from biothings_explorer.registry import Registry
  from biothings_explorer.user_query_dispatcher import SingleEdgeQueryDispatcher
  
  reg = Registry()
  
  class TestSingleHopQuery(unittest.TestCase):
  
      def test_gene2chemical(self):
          # test <chemical, target, gene>
          seqd = SingleEdgeQueryDispatcher(output_cls='ChemicalSubstance',
                                           input_cls='Gene',
                                           input_id='entrez',
                                           values='7852')
          seqd.query()
          self.assertTrue('ENFUVIRTIDE' in seqd.G)
          self.assertTrue('ENFUVIRTIDE' in seqd.G)
  
      def test_chemical2disease(self):
          # test <gene, targetedBy, chemical>
          seqd = SingleEdgeQueryDispatcher(input_cls='ChemicalSubstance',
                                           input_id='chebi',
                                           output_cls='DiseaseOrPhenotypicFeature',
                                           values='CHEBI:6601')
          seqd.query()
          self.assertTrue('non-small cell lung carcinoma (disease)' in seqd.G)
          self.assertTrue('poliomyelitis' in seqd.G)
          self.assertTrue('melanoma (disease)' in seqd.G)
  
      def test_chemical2gene(self):
          # test <gene, targetedBy, chemical>
          seqd = SingleEdgeQueryDispatcher(input_cls='ChemicalSubstance',
                                           input_id='chebi',
                                           output_cls='Gene',
                                           values='CHEBI:6601')
          seqd.query()
          self.assertTrue('HMGB1' in seqd.G)
          self.assertTrue('TP53' in seqd.G)
          self.assertTrue('TNF' in seqd.G)
  
subject: add cord test