anchor.diff:          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";
  
positive.code: 
    tomcat7 = common {
      versionMajor = "7";
      versionMinor = "0.70";
      sha256 = "0x4chqb7kkmadmhf2hlank856hw2vpgjl14fak74ybimlcb3dwqk";
    };
  
    tomcat8 = common {
  
negative.code:     versionMinor = "5.5";
      sha256 = "0idfxjrw5q45f531gyjnv6xjkbj9nhy2v1w4z7558z96230a0fqj";
    };
  
    tomcatUnstable = common {
      versionMajor = "9";
      versionMinor = "0.0.M10";
      sha256 = "0p3pqwz9zjvr9w73divsyaa53mbazf0icxfs06wvgxsvkbgj5gq9";
    };
  
  }
  