anchor.diff:  { lib, buildPythonPackage, fetchFromGitHub
   , isPy3k, attrs, coverage, enum34, pexpect
   , doCheck ? true, pytest, pytest_xdist, flaky, mock
  +, sortedcontainers
   }:
   buildPythonPackage rec {
     # https://hypothesis.readthedocs.org/en/latest/packaging.html
  
positive.code:   # pytz fake_factory django numpy pytest
    # If you need these, you can just add them to your environment.
  
    version = "4.41.0";
    pname = "hypothesis";
  
    # Use github tarballs that includes tests
  
negative.code:     owner = "HypothesisWorks";
      repo = "hypothesis-python";
      rev = "hypothesis-python-${version}";
      hash = "sha256:1ca2dwih65s4r8vazwqm963ywngdr3v854ldnfyny7bvx1v28m8k";
    };
  
    postUnpack = "sourceRoot=$sourceRoot/hypothesis-python";
  
    propagatedBuildInputs = [
      attrs
      coverage
      sortedcontainers
    ] ++ lib.optional (!isPy3k) enum34;
  
    checkInputs = [ pytest pytest_xdist flaky mock pexpect ];
    inherit doCheck;
  