Trace-co
The trace character output channel
See io for relevant background. (Trace-co state) is an
open character output channel. Trace output is printed to this
channel. Evaluate (set-trace-co CHAN state) to set (Trace-co state)
to the channel, CHAN.
``Trace-co'' stands for ``trace character output.'' The initial value of
trace-co is the same as the value of *standard-co*.
