my $least = min(keys %hash);
my $largest = max(keys %hash);

##</code><code>##

sub max {
  my $max = shift;
  $max = ($max < $_) ? $_ : $max foreach @_;
  return $max;
}

##</code><code>##

sub reduce (&@) {
  my $op = shift;
  no strict 'refs';
  my $pkg = caller;
  local *A = local *{"$pkg\::a"};
  $A  = shift;
  local *B = local *{"$pkg\::b"};
  foreach $B (@_) {
    $A = $op->();
  }
  $A;
}

##</code><code>##

sub max {
  reduce {$a > $b ? $a : $b } @_;
}

##</code><code>##

sub sum {
  reduce {$a + $b} @_;
}