## "Devel" - extra checking code
    local 
    *validate_returned_pointer = sub ($$) {
      my ($rp,$mpn)=@_;
      my $refp= ref $rp;
      $refp || die P "$self: undef inode returned in arg# %d", $mpn;
      $rp->can('Ino') || die P "$self: Bad type: %s: Cannot get ".
                                "Ino num in arg# %d", $refp, $mpn;
      $rp->Deleted_Ino_chk &&
        die P "$self: Deleted Ino returned in arg# %d", $mpn; 
      };

    use constant first_call       =>  1;
    use constant subsequent_call  =>  2;

    local * param_checks = sub ($) {
      if (scalar @$retp) {
        die "Error -- passed back params when Size index and\n".
            "next_in_Q are in pre-run state (%s, %s)", $mp->{Size2ss_nodes},
            $mp->{nextbase} unless $mp->{Size2ss_nodes} || $mp->{nextbase};
            TPe "$self: received %s params", scalar @$retp;

        die P "$self: Too many arguments (%s)", scalar @$retp if @$retp > 2;
                                              # validate returned pointers
        for (my $mpn = 0; $mpn <= $#$retp; ++$mpn) {
          validate_returned_pointer($retp->[$mpn], $mpn); }
        return subsequent_call;
      } else {
        die "$self: takes 1 or 2 params: a surviving inode\n".
            "if a link occurred, or both there was no linking.",
            if $mp->{size_idx} != 0;
        return first_call;
      }
    };

    state $exec;    #performs same 'function' as first/subseq call w/o checks 

    if (($mp->{optimize} and $exec||=$exec++) || 
                                          param_checks() == subsequent_call) {