def key_value(self, **kwargs):
        """
        Set fields to be key-value represented.

        :rtype: Column

        :Example:

        >>> new_ds = df.key_value('f1 f2', kv=':', item=',')
        """
        field_name = self.name
        new_df = copy_df(self)
        new_df._perform_operation(op.FieldKVConfigOperation({field_name: KVConfig(**kwargs)}))
        return new_df
Set fields to be key-value represented.

        :rtype: Column

        :Example:

        >>> new_ds = df.key_value('f1 f2', kv=':', item=',')