my @buffer = ();
my $length = scalar @sourcedata;

for (my $I = 0; $I < $length; $I++) {
  my $line = $sourcedata[$I];
  if ($line =~ /^1$/) {
    push(@buffer, $line);
    $I++;
    $line = $sourcedata[$I];

    # Here's the loop I can't seem to execute:
    while ($line =~ /^\n$/ && $I != $length) {
      print "Buffering...\n";
      push(@buffer, $line);
      $I++;
      last if $I == $length;
      $line = $sourcedata[$I];
    }
    if ($line =~ /_____ 2/) {
      # print only the first and last items in the buffer,
      # effectively removing the empty lines
      print shift(@buffer), pop(@buffer);
      print $line;
    }
    else {
      print join(@buffer);
    }
  }
  else {
    print $line;
  }
  @buffer = ();
}