.. change::
    :tags: feature, orm
    :tickets: 3162

    Added new parameter :paramref:`_sql.Operators.op.python_impl`, available
    from :meth:`_sql.Operators.op` and also when using the
    :class:`_sql.Operators.custom_op` constructor directly, which allows an
    in-Python evaluation function to be provided along with the custom SQL
    operator. This evaluation function becomes the implementation used when the
    operator object is used given plain Python objects as operands on both
    sides, and in particular is compatible with the
    ``synchronize_session='evaluate'`` option used with
    :ref:`orm_expression_update_delete`.
