verbatimtex
\input latex.pre
etex

beginfig(1);
numeric u;
u=5mm;

z1=(2u,u);
z2=(0.4u,2.2u);
z6=(4u,3.6u);
z7=(1.8u,2.8u);
z3-z2=z5-z6=z4-z8=z7-z1;
z8-z6=z2-z1;
draw z1--z2--z3--z4--z5--z6;
draw z2--z8;
draw z7--z1 dashed evenly;
draw z7--z3 dashed evenly;
draw z7--z5 dashed evenly;
draw z1--z6--z8--z4 withpen pencircle scaled 2pt;
x9=x10=x11=x12=5u;
y9=y1;y10=y6;y11=y8;y12=y4;
z13=(-0.2)[z9,z12];
z14=(1.2)[z9,z12];
draw z13--z14;
draw z9--z12 withpen pencircle scaled 2pt;
draw z1--z9 dashed evenly;
draw z6--z10 dashed evenly;
draw z8--z11 dashed evenly;
draw z4--z12 dashed evenly;
draw z1 withpen pencircle scaled 4pt;
draw z6 withpen pencircle scaled 4pt;
draw z8 withpen pencircle scaled 4pt;
draw z4 withpen pencircle scaled 4pt;
draw z9 withpen pencircle scaled 4pt;
draw z10 withpen pencircle scaled 4pt;
draw z11 withpen pencircle scaled 4pt;
draw z12 withpen pencircle scaled 4pt;
endfig;
bye
