to_json, from_json

class Foo:
    def __init__(self, a, b, c):
        self.a, self.b, self.c = a, b, c

    def to_json(self):
        return json.dumps({'a': self.a, 'b': self.b, 'c': self.c})

    @classmethod
    def from_json(cls, content):
        return cls(**json.loads(content))