anchor.diff:     return unpack(pack(reverse(bytes)));
   endfunction
   
  +function alpha apply_changes (alpha data, alpha metadata, alpha mask)
  +   provisos (Bits#(alpha, asz),
  +             Bitwise#(alpha));
  +   return (data & mask) | metadata;
  +endfunction
  +
   function Bool fifoNotEmpty(FIFOF#(a) fifo);
      return fifo.notEmpty();
   endfunction
  
positive.code:    t defaultMask;
  endtypeclass
  
  endpackage
  
negative.code: 
  package Utils;
  
  import GetPut::*;
  import FIFOF::*;
  import Vector::*;
  import ClientServer::*;
  
  typedef 8'h07 Idle;
  typedef 8'h55 Preamble;
  