code: def sparse_subtract(x1, x2):
      """Subtraction for `tf.SparseTensor`s.
  
      Either `x1` or `x2` or both can be `tf.SparseTensor`s.
  
      Args:
          x1: fist tensor to add.
          x2: second tensor to add.
      Returns:
          The sum of `x1` and `x2`, which is a `tf.SparseTensor` if and only if
          both `x1` or `x2` are `tf.SparseTensor`s.
      """
      if isinstance(x2, tf.SparseTensor):
          return tf.sparse.add(
              x1, tf.sparse.map_values(tf.negative, x2)
          )
      else:
          return tf.sparse.add(x1, tf.negative(x2))
  
file_path: keras/keras/backend/tensorflow/sparse.py
imports: import functools
  import tensorflow
label_desc: Use image node_id 5 for calling a global function with example usage: sparse_subtract(x1, x2) and returns: tf, tf