anchor.diff: -{ stdenv, autoreconfHook, coreutils, fetchFromGitHub, fetchpatch, pkgconfig
  +{ stdenv, autoreconfHook, coreutils, fetchFromGitHub, fetchpatch, pkgconfig, procps
   # pyflame needs one python version per ABI
   # are currently supported
   # * 2.6 or 2.7 for 2.x ABI
  
positive.code:     # don't use patchShebangs here to be explicit about the python version
      substituteInPlace utils/flame-chart-json \
        --replace '#!usr/bin/env python' '#!${python3.interpreter}'
    '';
  
    postInstall = ''
  
negative.code:     full-ptrace-seize-errors
    ];
  
    nativeBuildInputs = [ autoreconfHook pkgconfig procps ];
    buildInputs = [ python37 python36 python2 python35 ];
  
    postPatch = ''
      patchShebangs .
  
      # some tests will fail in the sandbox
      substituteInPlace tests/test_end_to_end.py \
        --replace 'skipif(IS_DOCKER' 'skipif(True'
  