def get_raw_token(self, header: bytes) -> Optional[bytes]:
        """
        Extracts an unvalidated JSON web token from the given "Authorization"
        header value.
        """
        parts = header.split()

        if len(parts) == 0:
            # Empty AUTHORIZATION header sent
            return None

        if parts[0] not in AUTH_HEADER_TYPE_BYTES:
            # Assume the header does not contain a JSON web token
            return None

        if len(parts) != 2:
            raise AuthenticationFailed(
                _("Authorization header must contain two space-delimited values"),
                code="bad_authorization_header",
            )

        return parts[1]

        Extracts an unvalidated JSON web token from the given "Authorization"
        header value.
        
rest_framework_simplejwt/authentication.py