Found using: https://github.com/intgr/topy

a join condition that is strictly from a single column to itself,
translated through some kind of SQL function or expression.  This
is kind of experimental, but the first proof of concept is a
"materialized path" join condition where a path string is compared
to itself using "like".   The :meth:`.Operators.like` operator has
also been added to the list of valid operators to use in a primaryjoin
condition.  fixes #3029

could inappropriately pull in the parent table, and also return results
inconsistent based on what's in the parent table, when the primaryjoin
includes some kind of discriminator against the parent table, such
as ``and_(parent.id == child.parent_id, parent.deleted == False)``.
While this primaryjoin doesn't make that much sense for a one-to-many,
it is slightly more common when applied to the many-to-one side, and
the one-to-many comes as a result of a backref.
Loading rows from ``child`` in this case would keep ``parent.deleted == False``
as is within the query, thereby yanking it into the FROM clause
and doing a cartesian product.  The new behavior will now substitute
the value of the local "parent.deleted" for that parameter as is
appropriate.   Though typically, a real-world app probably wants to use a
different primaryjoin for the o2m side in any case.
fixes #2948

to specify the string ``"nested"``.  When set to ``"nested"`` as opposed
to ``True``, the "chaining" of joins will parenthesize the inner join on the
right side of an existing outer join, instead of chaining as a string
of outer joins.   This possibly should have been the default behavior
when 0.9 was released, as we introduced the feature of right-nested
joins in the ORM, however we are keeping it as a non-default for now
to avoid further surprises.
fixes #2976

about non-equality operators in general.

- convert all paramter references in relationship documentation to :paramref: