We haven't written any error handling functions. But you can set the bash
environment variable OCAMLRUNPARAM to inclue "p" which will make ocamllex and
ocamlyacc verbose.

e.g. to turn on
$ export OCAMLRUNPARAM="p"

e.g. to turn off
$ export OCAMLRUNPARAM=""

This is really useful when you're getting parse errors but have no idea why.

Running ocamlyacc with the -v flag (see our Makefile) can help if you're
getting shift/reduce conflicts. This outputs a file called parser.output
that has information about states and conflicts.
