[ [[[[]]], [[]]], [[[]], []], [[]] ]

    Adding brackets to highlight the nesting of the arrayrefs:    
    [ ([ ([[[ ]]]) , ([[ ]])) ]),    ([ ([[ ]]) , ([ ]) ]),    ([ ([ ]) ])  ]
             4          2                  2        1               1
    
    This gives:
    
    = 2**(4+2) +2**(2+1) +2**(1)

    = 2**(6) +2**(3) +2**(1)
    
    = 1001010b
    
    = 74
    
    = ord('J');