Extract grant_type and route to the designated handler.

def create_token_response(self, uri, http_method='GET', body=None,
                              headers=None, credentials=None, grant_type_for_scope=None,
                              claims=None):
        """Extract grant_type and route to the designated handler."""
        request = Request(
            uri, http_method=http_method, body=body, headers=headers)

        # 'scope' is an allowed Token Request param in both the "Resource Owner Password Credentials Grant"
        # and "Client Credentials Grant" flows
        # https://tools.ietf.org/html/rfc6749#section-4.3.2
        # https://tools.ietf.org/html/rfc6749#section-4.4.2
        request.scopes = utils.scope_to_list(request.scope)

        request.extra_credentials = credentials
        if grant_type_for_scope:
            request.grant_type = grant_type_for_scope

        # OpenID Connect claims, if provided.  The server using oauthlib might choose
        # to implement the claims parameter of the Authorization Request.  In this case
        # it should retrieve those claims and pass them via the claims argument here,
        # as a dict.
        if claims:
            request.claims = claims

        grant_type_handler = self.grant_types.get(request.grant_type,
                                                  self.default_grant_type_handler)
        log.debug('Dispatching grant_type %s request to %r.',
                  request.grant_type, grant_type_handler)
        return grant_type_handler.create_token_response(
            request, self.default_token_type)