Create a paste and return the paste id.

def paste(self):
        """Create a paste and return the paste id."""
        data = json.dumps(
            {
                "description": "Werkzeug Internal Server Error",
                "public": False,
                "files": {"traceback.txt": {"content": self.plaintext}},
            }
        ).encode("utf-8")
        try:
            from urllib2 import urlopen
        except ImportError:
            from urllib.request import urlopen
        rv = urlopen("https://api.github.com/gists", data=data)
        resp = json.loads(rv.read().decode("utf-8"))
        rv.close()
        return {"url": resp["html_url"], "id": resp["id"]}