anchor.diff:      depend on additional packages.
   
   `perl-ModuleBuild`::
  -    For packages that use the Perl [Module::Build](http://search.cpan.org/~leont/Module-Build-0.4202/lib/Module/Build.pm) method.
  +    For packages that use the Perl
  +    http://search.cpan.org/~leont/Module-Build-0.4202/lib/Module/Build.pm[Module::Build] method.
   
   `perl`::
  -    For packages that use the standard Perl [ExtUtils::MakeMaker](http://perldoc.perl.org/ExtUtils/MakeMaker.html) build method.
  +    For packages that use the Perl
  +    http://perldoc.perl.org/ExtUtils/MakeMaker.html[ExtUtils::MakeMaker] build method.
   
   `python-module`::
       For packages that use the Python module build method (setup.py).
  
positive.code: `waf3`::
     For packages that use the Python3 `waf` build method with python3.
  
  `waf`:
     For packages that use the Python `waf` method with python2.
  
  source section - functions
  --------------------------
  
  The following functions can be defined to change the behavior of how the package is downloaded, compiled and installed.
  
  `do_fetch`::
      if defined and `distfiles` is not set, use it to fetch the required sources.
  
negative.code:   distfiles="http://www.foo.org/foo-${version}.tar.gz"
    checksum="fea0a94d4b605894f3e2d5572e3f96e4413bcad3a085aae7367c2cf07908b2ff"
    # end of source section
    # package section
    foo_package() {
      pkg_install() {
  