Initialize the class from a dict.

        :param dict_in: The dictionary that contains the item content. Required
            fields are listed class variable by that name
        :type dict_in: dict

def from_dict(cls, dict_in):
        """Initialize the class from a dict.

        :param dict_in: The dictionary that contains the item content. Required
            fields are listed class variable by that name
        :type dict_in: dict
        """
        kwargs = dict_in.copy()
        args = [kwargs.pop(key) for key in cls.required_fields]
        return cls(*args, **kwargs)