code: def cos_distance(t1, t2, epsilon=1e-12, name=None):
    
    with tf.name_scope(name, 'cos_distance', [t1, t2]) as scope:
      t1 = tf.convert_to_tensor(t1, name='t1')
      t2 = tf.convert_to_tensor(t2, name='t2')
      x_inv_norm = tf.rsqrt(tf.maximum(length_squared(t1) * length_squared(t2),
                                       epsilon))
      return tf.subtract(1.0, dot_product(t1, t2) * x_inv_norm, name=scope)
docs: Cos distance between t1 and t2 and caps the gradient of the Square Root.
  
    Args:
      t1: A tensor
      t2: A tensor that can be multiplied by t1.
      epsilon: A lower bound value for the distance. The square root is used as
        the normalizer.
      name: Optional name for this op.
    Returns:
      The cos distance between t1 and t2.