$package !~ /^\w[\w\:\']*\w?\z/
  || $package !~ /\w\z/
  || $package =~ /:/ && $package !~ /::/
  || $package =~ /\w:\w/
  || $package =~ /:::/

##</code><code>##

/^[A-Za-z0-9_]+(::[A-Za-z0-9_]+)*$/