def _expectation(p, kern, feat, none2, none3):
if not kern.on_separate_dimensions:
raise NotImplementedError("Product currently needs to be defined on separate dimensions.") // pragma: no cover
with tf.control_dependencies([
tf.assert_equal(tf.rank(p.var), 2,
message="Product currently only supports diagonal Xcov.", name="assert_Xcov_diag"),
]):
_expectation_fn = lambda k: _expectation(p, k, feat, None, None)
return functools.reduce(tf.multiply, [_expectation_fn(k) for k in kern.kern_list])