def get_access_token(self, http=None, additional_claims=None):
if additional_claims is None:<EOL><INDENT>if self.access_token is None or self.access_token_expired:<EOL><INDENT>self.refresh(None)<EOL><DEDENT>return client.AccessTokenInfo(<EOL>access_token=self.access_token, expires_in=self._expires_in())<EOL><DEDENT>else:<EOL><INDENT>token, unused_expiry = self._create_token(additional_claims)<EOL>return client.AccessTokenInfo(<EOL>access_token=token, expires_in=self._MAX_TOKEN_LIFETIME_SECS)<EOL><DEDENT>
Create a signed jwt.

        Args:
            http: unused
            additional_claims: dict, additional claims to add to
                the payload of the JWT.
        Returns:
            An AccessTokenInfo with the signed jwt