code: def pad_tensor_dict(tensor_dict, max_len):
      """Pad dictionary of tensors with zeros.
  
      Args:
          tensor_dict (dict[numpy.ndarray]): Tensors to be padded.
          max_len (int): Maximum length.
  
      Returns:
          dict[numpy.ndarray]: Padded tensor.
      """
      keys = list(tensor_dict.keys())
      ret = dict()
      for k in keys:
          if isinstance(tensor_dict[k], dict):
              ret[k] = pad_tensor_dict(tensor_dict[k], max_len)
          else:
              ret[k] = pad_tensor(tensor_dict[k], max_len)
  
      return ret
  
imports: import collections
  import numpy
  import tensorflow
label_desc: Use image node_id 18 for calling a global function with example usage: pad_tensor_dict(tensor_dict, max_len) and returns: ret