You can use a lexically scoped scalar as your file handle and return it. This will prevent you from overwriting one open filehandle with another. I would advise always using lexically scoped scalars for file handles (it is just generally safer). See the below example:

sub myopen {
   my ($file, $mode, $locktype) = @_;
   
   #open the file...for the sake of brevity
   #I'll not include the mode logic here
   if (open(my $fh, "$file")){
      print "Opened $file successfully.\n";
      #lock the file
      #do whatever else needs to be done
      return $fh;
   } else {
      warn "Can't open: $!\n";
   }
}
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