docs: def concat(self, second_iterable):
          '''Concatenates two sequences.
  
          Note: This method uses deferred execution.
  
          Args:
              second_iterable: The sequence to concatenate on to the sequence.
  
          Returns:
              A Queryable over the concatenated sequences.
  
          Raises:
              ValueError: If the Queryable is closed().
              TypeError: If second_iterable is not in fact iterable.
          '''
          if self.closed():
              raise ValueError("Attempt to call concat() on a closed Queryable.")
  
          if not is_iterable(second_iterable):
              raise TypeError("Cannot compute concat() with second_iterable of "
                    "non-iterable {0}".format(str(type(second_iterable))[7: -1]))
  
          return self._create(itertools.chain(self, second_iterable))