prologues := 3;
% `mpost filename.mp` produces encapsulated EPS.
% Convert to pdf with `mptopdf -raw hello.mp`
beginfig(3)
pair a,b;
path p;
pen mypen;
a = (0,0);
b = (3,4);
p = a--b;
mypen = pencircle scaled 1;
pickup mypen;
draw p;
endfig;
end