`DiscretePolicyEstimator` has no printable representation

[brunorousseau]

The class DiscretePolicyEstimator derives from GFNModule. This parent class implements __repr__ by making explicit reference to an environment:

The child class inherits this function, but has no env property. Thus, instances of the child class cannot be printed:

[saleml]

Thank you for raising the issue. It will be fixed in an imminent release.