anchor.diff:  buildPythonPackage rec {
     pname = "nipype";
     version = "1.5.1";
  +  disabled = isPy27;
   
     src = fetchPypi {
       inherit pname version;
  
positive.code:     simplejson
      traits
      xvfbwrapper
    ] ++ stdenv.lib.optionals (!isPy3k) [
      configparser
      futures
      pathlib2 # darwin doesn't receive this transitively, but it is in install_requires
    ];
  
    checkInputs = [
  
negative.code: { stdenv
  , buildPythonPackage
  , fetchPypi
  , isPy27
  # python dependencies
  , click
  , dateutil
  , etelemetry
  , filelock
  , funcsigs
  , future
  , mock
  , networkx
  , nibabel
  , numpy
  , packaging
  , prov
  , psutil
  , pybids
  