anchor.diff:      versionMinor = "5.5";
       sha256 = "0idfxjrw5q45f531gyjnv6xjkbj9nhy2v1w4z7558z96230a0fqj";
     };
  -  
  +
     tomcatUnstable = common {
       versionMajor = "9";
       versionMinor = "0.0.M10";
       sha256 = "0p3pqwz9zjvr9w73divsyaa53mbazf0icxfs06wvgxsvkbgj5gq9";
     };
  -  
  +
   }
  
positive.code:   common = { versionMajor, versionMinor, sha256 } @ args: stdenv.mkDerivation (rec {
      name = "apache-tomcat-${version}";
      version = "${versionMajor}.${versionMinor}";
      
      src = fetchurl {
        url = "mirror://apache/tomcat/tomcat-${versionMajor}/v${version}/bin/${name}.tar.gz";
        inherit sha256;
      };
      
      outputs = [ "out" "webapps" ];
      installPhase =
        ''
  
negative.code:         mkdir -p $webapps/webapps
          mv $out/webapps $webapps/
        '';
  
      meta = {
        homepage = https://tomcat.apache.org/;
        description = "An implementation of the Java Servlet and JavaServer Pages technologies";
  