PPI provides the ability to parse, analyze and manipulate Perl code without
 actually executing the code, by implementing a lexer similar to what perl has
 itself internally.
 .
 The purpose of PPI is not to parse Perl Code, but to parse Perl Documents. By
 making this distinction and treating the problem this way, one could analyze
 files containing Perl source code in isolation from any other resources and
 without executing it, including other libraries. A significant feature of PPI
 is the ability to analyze Perl source code without requiring an instance of
 perl to run alongside or inside the parser.