docs: def iterator_zip(variables: VarType, parent: str = None) -> Iterable[VarMatrix]:
      """Apply the zip operator to a set of variables.
  
      This uses the python zip iterator to combine multiple lists of variables such that
      the nth variable in each list is aligned.
  
      Args:
          variables: The variables object
          parent: Unused
  
      """
  
      logger.debug("Yielding from zip iterator")
      if isinstance(variables, list):
          for item in variables:
              yield list(variable_matrix(item, parent, "zip"))
      else:
          yield list(variable_matrix(variables, parent, "zip"))