anchor.diff:        else
           s;
   
  -  # Return true iff string v1 denotes a version older than v2.
  +  /* Return true iff string v1 denotes a version older than v2.
  +
  +     Example:
  +       versionOlder "1.1" "1.2"
  +       => true
  +       versionOlder "1.1" "1.1"
  +       => false
  +  */
     versionOlder = v1: v2: builtins.compareVersions v2 v1 == 1;
   
  -
  -  # Return true iff string v1 denotes a version equal to or newer than v2.
  +  /* Return true iff string v1 denotes a version equal to or newer than v2.
  +
  +     Example:
  +       versionAtLeast "1.1" "1.0"
  +       => true
  +       versionAtLeast "1.1" "1.1"
  +       => true
  +       versionAtLeast "1.1" "1.2"
  +       => false
  +  */
     versionAtLeast = v1: v2: !versionOlder v1 v2;
   
  -
  -  # This function takes an argument that's either a derivation or a
  -  # derivation's "name" attribute and extracts the version part from that
  -  # argument. For example:
  -  #
  -  #    lib.getVersion "youtube-dl-2016.01.01" ==> "2016.01.01"
  -  #    lib.getVersion pkgs.youtube-dl         ==> "2016.01.01"
  +  /* This function takes an argument that's either a derivation or a
  +     derivation's "name" attribute and extracts the version part from that
  +     argument.
  +
  +     Example:
  +       getVersion "youtube-dl-2016.01.01"
  +       => "2016.01.01"
  +       getVersion pkgs.youtube-dl
  +       => "2016.01.01"
  +  */
     getVersion = x: (builtins.parseDrvName (x.name or x)).version;
   
  -
  -  # Extract name with version from URL. Ask for separator which is
  -  # supposed to start extension.
  +  /* Extract name with version from URL. Ask for separator which is
  +     supposed to start extension.
  +
  +     Example:
  +       nameFromURL "https://nixos.org/releases/nix/nix-1.7/nix-1.7-x86_64-linux.tar.bz2" "-"
  +       => "nix"
  +       nameFromURL "https://nixos.org/releases/nix/nix-1.7/nix-1.7-x86_64-linux.tar.bz2" "_"
  +       => "nix-1.7-x86"
  +  */
     nameFromURL = url: sep:
       let
         components = splitString "/" url;
  
positive.code:     in
        recurse 0 0;
  
  
    # return the suffix of the second argument if the first argument match its
    # prefix. e.g.,
    # `removePrefix "foo." "foo.bar.baz"' returns "bar.baz".
    removePrefix = pre: s:
      let
        preLen = stringLength pre;
  
negative.code:       absolutePaths = builtins.map (path: builtins.toPath (root + "/" + path)) relativePaths;
      in
        absolutePaths;
  }
  