code: def create_or_update(self, store_id, product_id, variant_id, data):
          
          self.store_id = store_id
          self.product_id = product_id
          self.variant_id = variant_id
          if 'id' not in data:
               raise KeyError('The product variant must have an id')
          if 'title' not in data:
              raise KeyError('The product variant must have a title')
          return self._mc_client._put(
              url=self._build_path(store_id, 'products', product_id, 'variants', variant_id),
              data=data
          )
docs: Add or update a product variant.
  
          :param store_id: The store id.
          :type store_id: :py:class:`str`
          :param product_id: The id for the product of a store.
          :type product_id: :py:class:`str`
          :param variant_id: The id for the product variant.
          :type variant_id: :py:class:`str`
          :param data: The request body parameters
          :type data: :py:class:`dict`
          data = {
              "id": string*,
              "title": string*
          }