docs: def get_index(self, key):
          """
          Returns an address by input index, a value that matches the list index of the provided
          lookup value, not necessarily the result.
  
          :param key: an input_index matching the index of the provided address
          :return: a matching Address
          """
          try:
              return self[self.index_lookup.get(key)]
  
          except TypeError:
              raise KeyError