[R] drawing a curly bracket in a plot

[Jonathan Baron]

I need to re-draw a graph that consists of a few lines.  Next to
each line is a curly bracket - like { - with its ends near the
ends of the line.  (At the point of the bracket is some sort of
label, but that is done with text() or something like that.)
Some brackets are horizontal, some are vertical, and some are
diagonal.

I can't find any code for this.  Has anyone done it?

Jon