code: def to_header(self, timestamp=None):
          
          rv = [("sentry_key", self.public_key), ("sentry_version", self.version)]
          if timestamp is not None:
              rv.append(("sentry_timestamp", str(to_timestamp(timestamp))))
          if self.client is not None:
              rv.append(("sentry_client", self.client))
          if self.secret_key is not None:
              rv.append(("sentry_secret", self.secret_key))
          return u"Sentry " + u", ".join("%s=%s" % (key, value) for key, value in rv)
docs: Returns the auth header a string.