accept methods as callbacks as well

Signed-off-by: Tomas Tomecek <ttomecek@redhat.com>

fedora_messaging/_session.py

@@ -495,7 +495,7 @@ def consume(self, callback, bindings=None, queues=None, exchanges=None):
                     " or a function."
                 )
             self._consumer_callback = cb_obj
-        elif inspect.isfunction(callback):
+        elif inspect.isfunction(callback) or inspect.ismethod(callback):
             self._consumer_callback = callback
         else:
             raise ValueError(