{
      for 0..$.max -> $y 
      {
        block($x,$y);
      }
    }
  }

  method calculate() is private 
  {
    my @newgrid;
    iterate
    { 
      my $live = sum(@.grid[$^x-1..$^x+1][$^y-1..$^y+1]);
      @newgrid[$^x][$^y] =  $live==2 && @.grid[$^x][$^y] 
                         || $live==3;
    }