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This is just a bugfix and performance release, but it changes some
semi-public APIs, hence the minor version bump.
* Significant performance improvements for strategies which are one\_of()
many branches. In particular this included recursive() strategies. This
should take the case where you use one recursive() strategy as the base
strategy of another from unusably slow (tens of seconds per generated
example) to reasonably fast.
* Better handling of just() and sampled_from() for values which have an
incorrect \_\_repr\_\_ implementation that returns non-ASCII unicode
on Python 2.
* Better performance for flatmap from changing the internal morpher API
to be significantly less general purpose.
* Introduce a new semi-public BuildContext/cleanup API. This allows
strategies to register cleanup activities that should run once the
example is complete. Note that this will interact somewhat weirdly with
find.
* Better simplification behaviour for streaming strategies.
* Don't error on lambdas which use destructuring arguments in Python 2.
* Add some better reprs for a few strategies that were missing good ones.
* The Random instances provided by randoms() are now copyable.
* Slightly more debugging information about simplify when using a debug
verbosity level.
* Support using given for functions with varargs, but not passing arguments
to it as positional.