<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def add_rule(self, binding_type: str, rule: BindingRule):
 """Adds new rule"""

        if binding_type not in self._rules:
            self._rules[binding_type] = []

        self._rules[binding_type].insert(0, rule)