The package emulates large parts of TeX's behaviour when it
chews on tokens, expanding and performing typesetting commands.
Using unravel will let you go one step at a time through some
complicated LaTeX code that you are trying to debug. It
understands a whole breadth of TeX's features, from deeply
nested expansion to box assignments, to characters, and the
proper insertion of \everypar. The unravel package requires up-
to-date l3kernel and l3experimental bundles, as well as the new
package gtl.