Look up a type, following the class hierarchy. e.g. "Mode", if ContextClassName is A, will be looked as A::Mode, then as B::Mode (if B is a parent class of A), then as Qt::Mode, then as just Mode.
To install Ast, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Ast
CPAN shell
perl -MCPAN -e shell install Ast
For more information on module installation, please visit the detailed CPAN module installation guide.