\begin{tikzpicture}[x=1ex,y=1ex,baseline={([yshift=-.5ex]current bounding box.center)}]
    \coordinate (v0);
    \coordinate [right=1.5 of v0] (v1);
    \coordinate [left=.7 of v0] (i0); 
    \coordinate [right=.7 of v1] (o0); 
    \draw[thick,col1] (v0) -- (v1);
    \filldraw (v0) circle (1pt);
    \filldraw (v1) circle (1pt);
    \draw (i0) circle(.7);
    \draw (o0) circle(.7);
\end{tikzpicture}%
