sub example_method {
   my $self = shift;
   my %args;
   {
     my %raw_args = @_;
     %args = map {lc($_) => $raw_args{$_}} keys %raw_args;
   }
   unless ($args{'handle'}) {
     croak("Missing 'handle' argument");
   }
   unless ($args{'thing'}) {
     croak("Missing 'thing' argument");
   }
   unless (4 == @_) {
     croak("Unexpected extra parameters");
   }
   my ($handle,$thing) = @args{'handle','thing'};
   #...
 }