code: def flatten_up_to(shallow_tree, input_tree):
      """Flattens `input_tree` up to `shallow_tree`.
  
      Any further depth in structure in `input_tree` is retained as elements in the
      partially flatten output.
  
      If `shallow_tree` and `input_tree` are not sequences, this returns a
      single-element list: `[input_tree]`.
  
      Use Case:
  
      Sometimes we may wish to partially flatten a nested sequence, retaining some
      of the nested structure. We achieve this by specifying a shallow structure,
      `shallow_tree`, we wish to flatten up to.
  
      The input, `input_tree`, can be thought of as having the same structure as
      `shallow_tree`, but with leaf nodes that are themselves tree structures.
  
      Examples:
  
      ```python
      input_tree = [[[2, 2], [3, 3]], [[4, 9], [5, 5]]]
      shallow_tree = [[True, True], [False, True]]
  
      flattened_input_tree = flatten_up_to(shallow_tree, input_tree)
      flattened_shallow_tree = flatten_up_to(shallow_tree, shallow_tree)
  
      # Output is:
      # [[2, 2], [3, 3], [4, 9], [5, 5]]
      # [True, True, False, True]
      ```
  
      ```python
      input_tree = [[('a', 1), [('b', 2), [('c', 3), [('d', 4)]]]]]
      shallow_tree = [['level_1', ['level_2', ['level_3', ['level_4']]]]]
  
      input_tree_flattened_as_shallow_tree = flatten_up_to(shallow_tree, input_tree)
      input_tree_flattened = flatten(input_tree)
  
      # Output is:
      # [('a', 1), ('b', 2), ('c', 3), ('d', 4)]
      # ['a', 1, 'b', 2, 'c', 3, 'd', 4]
      ```
  
      Non-Sequence Edge Cases:
  
      ```python
      flatten_up_to(0, 0)  # Output: [0]
      flatten_up_to(0, [0, 1, 2])  # Output: [[0, 1, 2]]
      flatten_up_to([0, 1, 2], 0)  # Output: TypeError
      flatten_up_to([0, 1, 2], [0, 1, 2])  # Output: [0, 1, 2]
      ```
  
      Args:
        shallow_tree: a possibly pruned structure of input_tree.
        input_tree: an arbitrarily nested structure or a scalar object.
          Note, numpy arrays are considered scalars.
  
      Returns:
        A Python list, the partially flattened version of `input_tree` according to
        the structure of `shallow_tree`.
  
      Raises:
        TypeError: If `shallow_tree` is a sequence but `input_tree` is not.
        TypeError: If the sequence types of `shallow_tree` are different from
          `input_tree`.
        ValueError: If the sequence lengths of `shallow_tree` are different from
          `input_tree`.
      """
      return nest_util.flatten_up_to(
          nest_util.Modality.DATA, shallow_tree, input_tree
      )
  
file_path: tensorflow/tensorflow/python/data/util/nest.py
imports: from tensorflow.python.util import nest_util
label_desc: Use image node_id 7 for calling a global function with example usage: flatten_up_to(shallow_tree, input_tree) and returns: nest_util