morse.py

class Letter:
    def __init__(self, pattern=None):
        self.pattern = pattern

    def __iter__(self):
        yield from self.pattern

    def __str__(self):
        output = []
        for blip in self:
            if blip == '.':
                output.append('dot')
            else:
                output.append('dash')
        return '-'.join(output)
    @classmethod
    def from_string(cls,string):
        output2 = []
        for bli in string:
            if bli =="dash":
                output2.append('_')

            elif bli =="dot":
                output2.append('.')
            else:
                break
        return cls(output2)



class S(Letter):
    def __init__(self):
         pattern = ['.', '.', '.']
         super().__init__(pattern)