Implement a sequent calculus in the style of the implementation of natural
deduction presented in class (see natded or natded.tgz). Your implementation should take a
proposed sequent derivation and either fail (if the derivation is incorrect),
or (if the derivation is correct) generate a proof term, whose validity can be
independently verified using an implementation of the ND2
signature. If you need to extend the ND2 signature to permit
additional operations, please carefully justify your extensions.
For this assignment, efficiency is not a concern.