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

% --- 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)
picture lab;
lab=btex $x$ etex;
ncline(a)(b) "labpic(lab)","labdir(top)";
drawObj(a,b);
endfig;
end;