while (<DATA>)
{
  1 while s/^ ~ .*? \K  _  /+/x;

  print "$_";
}


##</code><code>##


while (<DATA>)
{
  s/^ ~ .*? \K  ( .+ )  / ( my $x = $1 ) =~ tr-_-+-; $x /xe;

  print "$_";
}