my $square_this 
     = sub { my $x = shift; 
             return $x**2; 
           };

##</code><code>##

sub square 
{ 
    my $x = shift; 
    return $x**2; 
}
my $square_this = \&square;

##</code><code>##

my $squared = $square_this->($hypotenuse);

##</code><code>##

package Square;
sub square 
{ 
    my $x = shift; 
    return $x**2; 
}

##</code><code>##

my $squared = square($hypotenuse);

##</code><code>##

my $squared = Square::square($hypotenuse);

##</code><code>##

use Square qw(square);
my $squared = square($hypotenuse);

##</code><code>##

{ # closure for cubed

  my $square 
       = sub { my $x = shift; 
               return $x**2; 
             };

  sub cubed 
  { 
      my $z = shift; 
      return $z*$square->($z); 
  }

} # end closure for cubed