@classmethod
def from_dict(cls, spec_dict, origin_url=None, http_client=None, config=None):
    """Build a :class:`Spec` from Swagger API Specification

        :param spec_dict: swagger spec in json-like dict form.
        :param origin_url: the url used to retrieve the spec, if any
        :type  origin_url: str
        :param http_client: http client used to download remote $refs
        :param config: Configuration dict. See CONFIG_DEFAULTS.
        """
    spec = cls(spec_dict, origin_url, http_client, config)
    spec.build()
    return spec
