keras/src/backend/tensorflow/core.py/cast
def cast(x, dtype):
    dtype = standardize_dtype(dtype)
    if isinstance(x, tf.SparseTensor):
        x_shape = x.shape
        x = tf.cast(x, dtype)
        x.set_shape(x_shape)
        return x
    else:
        return tf.cast(x, dtype=dtype)