| line | !l | l&&!r | l&&r | condition | 
 
| 257 | 17297 | 0 | 14703 | defined $piece and $piece->can('clone') | 
 
| 270 | 0 | 0 | 269 | defined $caller and $$caller >= 0 | 
 
| 300 | 0 | 0 | 3 | defined $x and defined $y | 
 
| 311 | 0 | 0 | 22965 | defined $x and defined $y | 
 
| 313 | 480 | 500 | 21985 | $x >= 0 and $x <= 7 | 
 
| 321 | 0 | 0 | 23068 | defined $x and defined $y | 
 
| 323 | 476 | 500 | 22092 | $y >= 0 and $y <= 7 | 
 
| 375 | 1022 | 1949 | 1014 | $vdist and $hdelta == 0 | 
 
|  | 0 | 1949 | 1022 | $hdist and $vdelta == 0 | 
 
| 434 | 0 | 281 | 0 | 'Chess::Board'->square_is_valid($sq1) and 'Chess::Board'->square_is_valid($sq2) | 
 
| 451 | 161 | 120 | 0 | $hdist == 0 and $hdist == $vdist |