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- If a generic function implementation defines a ``lookup`` argument
that argument will be the lookup used to call it.
- Added ``reg.mapply()``. This allows you to call things with more
keyword arguments than it accepts, ignoring those extra keyword
args.
- A function that returns ``None`` is not assumed to fail, so no fallback
to the original generic function is triggered anymore.
- An optional ``precalc`` facility is made available on ``Matcher`` to
avoid some recalculation.
- Implement a specific ``PredicateMatcher`` that matches a value on
predicate.