What Moose is providing.

Cleanup.

no Moose;

This line removes any of Moose's exports from the module's namespace. You can use namespace::autoclean in place of this line if you want.

__PACKAGE__->meta->make_immutable();

This line tells Perl and Moose that this package is done being set-up -- we aren't going to add or alter any of its attributes. This line will also cause Moose to inline the class's constructor and create some class-specific code, which will make instantiating a class much faster.