0  ARRAY(0x600500ae8)
   0  empty slot   # $x starts as 1, so no element for subscript 0
   1  ARRAY(0x600500c68)
      0  'line1 file 1'
      1  'line2 file 1'
      2  ' ... etc.)
   2  ARRAY(0x600500b30)
      0  'line 1 file 2'
      2  ' ... etc.

   ... etc.

   75 ARRAY(0x6005.....)
      0  'line 1 file 75'
      2  ' ... etc.