code: def to_gremlin(self):
          
          translation_table = {
              u'size': u'count()',
          }
          gremlin_operator = translation_table.get(self.operator)
          if not gremlin_operator:
              raise AssertionError(u'Unrecognized operator used: '
                                   u'{} {}'.format(self.operator, self))
  
          template = u'{inner}.{operator}'
          args = {
              'inner': self.inner_expression.to_gremlin(),
              'operator': gremlin_operator,
          }
          return template.format(**args)
docs: Return a unicode object with the Gremlin representation of this expression.