code: def tuplize(nested):
      """Recursively converts iterables into tuples.
  
      Args:
        nested: A nested structure of items and iterables.
  
      Returns:
        A nested structure of items and tuples.
      """
      if isinstance(nested, str):
          return nested
      try:
          return tuple(map(tuplize, nested))
      except TypeError:
          return nested
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import functools
  import os
  import numpy
  from tensor2tensor.data_generators import problem
  from tensor2tensor.data_generators import text_problems
  import tensorflow.compat.v1
label_desc: Use image node_id 11 for calling a global function with example usage: tuplize(nested) and returns: nested, tuple, nested