above_below(edgelist, above)above = NULL
then all arcs are plotted above (or to the right) If
above is numeric, it cannot contain both positive
and negative indices. If above is logical, its
length must equal the number of rows in edgelisthorizontal = TRUE then arcs can be plotted
above or below the horizontal axis If
horizontal = FALSE then arcs can be plotted to the
right or left of the vertical axis