% --- start of displayed preamble in the book ---

% --- end of displayed preamble in the book ---
defaultfont:="ptmr8r";
warningcheck:=0;
beginfig(1)
for i=0 upto 5:
 draw (0,i*6mm)--(3cm,i*6mm);
endfor;
for i=0 upto 5:
 draw (i*6mm,0)--(i*6mm,3cm);
endfor;
endfig;
end;