anchor.diff:      version = 3;
       owner = "beevik";
       repo = "etree";
  -    rev = "09746331a38f3da8c023a85a65c8c152070de725";
  -    sha256 = "07a8s135jr3z6isplwbjah4zigsyhhnkq9azb5f75jkpglpwdqiv";
  -    date = "2017-05-11";
  +    rev = "15a30b44cfd6c5a16a7ddfe271bf146aaf2d3195";
  +    sha256 = "0h6lmwl8f4kqkgg3pi95bhpfrbq2a1ijdyqslx20ixlvgfvi9ywy";
  +    date = "2017-08-09";
     };
   
     ewma = buildFromGitHub {
  
positive.code:   };
  
    urlesc = buildFromGitHub {
      version = 2;
      owner = "PuerkitoBio";
      repo = "urlesc";
      rev = "bbf7a2afc14f93e1e0a5c06df524fbd75e5031e5";
      sate = "2015-02-08";
      sha256 = "0rmcdn7z2rvms4j3pjbwbydffgl4s9igcjcfyin47sss0ywf6pmd";
      date = "2017-03-24";
    };
  
    usage-client = buildFromGitHub {
  
negative.code: 
    aws-sdk-go = buildFromGitHub {
      version = 3;
      rev = "v1.10.24";
      owner  = "aws";
      repo   = "aws-sdk-go";
      sha256 = "1kbcsx7caa9fzjdn5rsxvr3w05mfq2daspy1cj7ldr2d1nm1bkyr";
      excludedPackages = "\\(awstesting\\|example\\)";
      buildInputs = [
        tools
  