my $text = "The cow jumped over the moon";
  $text =~ s/(\w+\s+)jumped/$1tripped/;

##</code><code>##

  if ( $text =~ m/cow\s+(jumped)\s+over/ ) {
    $1 = "tripped";
  }

##</code><code>##

  if ( $text =~ m/cow\s+(\w+)\s+over/ ) {
    do_action( $1 );
    $1 = calculate_new_action( $1 );
  }

##</code><code>##

  if ( $text =~ m/cow\s+(\w+)\s+over/ ) {
    do_action( $1 );
    my $new_action = calculate_new_action( $1 );
    $text =~ s/(cow\s+)(\w+)(\s+over)/$1$new_action$3/;
  }