docs: def getIndex(self, indexName, indexClass):
          """Retrieves an index with a given index name and class
          @params indexName: The index name
          @params indexClass: vertex or edge
  
          @return The Index object or None"""
          if indexClass == "vertex":
              try:
                  return Index(indexName, indexClass, "manual",
                          self.neograph.nodes.indexes.get(indexName))
              except client.NotFoundError:
                  return None
          elif indexClass == "edge":
              try:
                  return Index(indexName, indexClass, "manual",
                          self.neograph.relationships.indexes.get(indexName))
              except client.NotFoundError:
                  return None
          else:
              raise KeyError("Unknown Index Class (%s). Use vertex or edge"\
                      % indexClass)