anchor.diff:  { stdenv, fetchgit, fetchurl
   # build tools
  -, gfortran, git, m4, patchelf, perl, which
  +, gfortran, git, m4, patchelf, perl, which, python2
   # libjulia dependencies
   , libunwind, llvm, readline, utf8proc, zlib
   # standard library dependencies
  
positive.code:   '';
  
    buildInputs =
      [ libunwind llvm readline utf8proc zlib
        double_conversion fftw fftwSinglePrec glpk gmp mpfr pcre
        openblas arpack suitesparse
      ];
  
    nativeBuildInputs = [ gfortran git m4 patchelf perl which ];
  
    makeFlags =
      let
  
negative.code:       "USE_SYSTEM_GMP=1"
        "USE_SYSTEM_GRISU=1"
        "USE_SYSTEM_LIBUNWIND=1"
        "USE_SYSTEM_MPFR=1"
        "USE_SYSTEM_PATCHELF=1"
        "USE_SYSTEM_PCRE=1"
  