docs: def guest_resize_mem(self, userid, size):
          """Resize memory of guests.
  
          :param userid: (str) the userid of the guest to be resized
          :param size: (str) The memory size that the guest should have
                 defined in user directory after resize.
                 The value should be specified by 1-4 bits of number suffixed by
                 either M (Megabytes) or G (Gigabytes). And the number should be
                 an integer.
  
          """
          action = "resize guest '%s' to have '%s' memory" % (userid, size)
          LOG.info("Begin to %s" % action)
          with zvmutils.log_and_reraise_sdkbase_error(action):
              self._vmops.resize_memory(userid, size)
          LOG.info("%s successfully." % action)