def p_rule(self, rule):
        '''rule : GUIDELINE
                | REGULATION'''
        if len(rule[1]) == 4:
            # This is a guideline
            rule[0] = Guideline(rule[1][1], rule[1][2], rule[1][3])
        else:
            # This is a regulation
            indentsize = rule[1][0]
            number = rule[1][1]
            text = rule[1][2]
            parent = None

            # If we just "un"nested, shrink the current rule to our level
            if self.prev_indent > indentsize:
                self.current_rule = self.current_rule[0:indentsize+1]

            # We just added a nested level, the parent is the list's last elem
            if self.prev_indent < indentsize:
                parent = self.current_rule[-1]
            # Else, if we are nested the parent is the one before the last elem
            elif len(self.current_rule) > 1:
                parent = self.current_rule[-2]
            # Else if we are not nested, then we are a root rule and parent is none
            # (do nothing as parent is initialized to none)

            # Create the regulation node
            reg = Regulation(number, text, parent)

            # Let our parent knows he has a new child, if we don't have a parent
            # let's create an item in the article rules list
            if parent:
                parent.add_child(reg)
            else:
                rule[0] = reg

            # Unless we nested, pop and replace the last rule by ourself
            # If we added a nesting level, we just need to add ourself
            if self.prev_indent >= indentsize:
                self.current_rule.pop()
            self.current_rule.append(reg)
            self.prev_indent = indentsize
rule : GUIDELINE
                | REGULATION