Adds a new Arc
        Args:
            src (int): The source state identifier
            dst (int): The destination state identifier
            char (str): The character for the transition
        Returns:
            None

def add_arc(self, src, dst, char):
        """Adds a new Arc
        Args:
            src (int): The source state identifier
            dst (int): The destination state identifier
            char (str): The character for the transition
        Returns:
            None
        """
        if src not in self.automaton.states():
            self.add_state()
        arc = fst.Arc(self.isyms[char], self.osyms[char],  fst.Weight.One(self.automaton.weight_type()), dst)
        self.automaton.add_arc(src, arc)