P_rindex => sub {
    my $x = $X;
    while (1) { my $i = length($x); (rindex($x," ") == $i ? chop : last) };
  },
  F_rindex => sub {
    my $x = $Y;
    while (1) { my $i = length($x); (rindex($x," ") == $i ? chop : last) };
  },