% --- start of displayed preamble in the book ---
input metaobj
% Circles produced as before

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

  newCircle.a(btex start etex);
  newCircle.b(btex end etex);
  a.c=origin;
  b.c-a.c=(3cm,1cm);

defaultfont:="ptmr8r";
warningcheck:=0;
beginfig(1)
ncline(a)(b) "doubleline(true)",
  "nodesepB(10mm)", "arrows(draw)";
drawObj(a,b);
endfig;
end;