def test_tag_to_function(self):
"""
Try getting a function for every tag and check it's in the
set of allowed functions.
"""
g = Grammar()
for tag in g.pos_tags:
fun = g.tag_to_function(tag)
if fun is None:
warnings.warn("Tag %s has no function given by the "\
"grammar" % tag)
else:
self.assertIn(fun, ['T','D','S','Pass'])
