def remove(self, rule):
del self._rules[rule.condition]<EOL>
Remove this classifier rule from the action set. (Does not
        affect numerosity.) A KeyError is raised if the rule is not present
        in the action set when this method is called.

        Usage:
            if rule in action_set:
                action_set.remove(rule)

        Arguments:
            rule: The ClassifierRule instance to be removed.
        Return: None