code: def hsetnx(self, key, field, value):
          
          return self._execute([b'HSETNX', key, field, value])
docs: Sets `field` in the hash stored at `key` only if it does not exist.
  
          Sets `field` in the hash stored at `key` only if `field` does not
          yet exist.  If `key` does not exist, a new key holding a hash is
          created.  If `field` already exists, this operation has no effect.
  
          .. note::
  
             *Time complexity*: ``O(1)``
  
          :param key: The key of the hash
          :type key: :class:`str`, :class:`bytes`
          :param field: The field in the hash to set
          :type key: :class:`str`, :class:`bytes`
          :param value: The value to set the field to
          :returns: ``1`` if `field` is a new field in the hash and `value`
              was set.  ``0`` if `field` already exists in the hash and
              no operation was performed
          :rtype: int