Letter named from_string

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, stg):
        contain1 = []
        stg = stg.lower()
        stg = stg.split("-")
        print(stg)
        for item in stg:
            if item == "dash".lower():
                contain1.append("-")
            elif item == "dot".lower():
                contain1.append(".")
        return cls(contain1)


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