This is Perl module Graphviz::DSL.

INSTALLATION

Graphviz::DSL installation is straightforward.
If your CPAN shell is set up, you should just be able to do

    % cpan Graphviz::DSL

Download it, unpack it, then build it as per the usual:

    % perl Makefile.PL
    % make && make test

Then install it:

    % make install

DOCUMENTATION

Graphviz::DSL documentation is available as in POD.
So you can do:

    % perldoc Graphviz::DSL

to read the documentation online with your favorite pager.

Syohei YOSHIDA