Problem: McCarthy 91 function

Code: McCarthy+91+function/tails_1644921716

Nibbles version: 0.2 | 0.21 | 0.22 | 0.23 | 0.24 | 0.25 | 1.00

Format: Compact | Simple | +Type | Table | JSON | .nbl (DeBruijn) | .nbl (names)

<~ `. ~~ 1 
         $ 
         $ 
      ? - @ 
          ^ ~ 
            ~ 
        ~ - @ 
            ~ 
          - _ 
            10 
        + $ 
          ~ 
        + 11 
          @ 
      $ 
      @ 
   _ 
: : ^ $ 
      "M(" 
    @ 
  ^ $ 
    ")"