<'
struct constrain_gen_ex2 { 
  good: bool; 
  length: byte [1..24]; 
  data [length]: list of byte; 
  crc: uint; 
  keep good => crc == crc_calc(); 
  keep gen (length, data) before (crc); 
 
  crc_calc() : uint is { 
    result = pack(packing.low,length,data).crc_32(0,length); 
  }; 
}; 
 
extend sys { 
  tb : list of constrain_gen_ex2;
  run() is also { 
    print sys.tb.crc; 
  }; 
}; 
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