I know why you're here, Neo. I know what you've been doing... why you hardly sleep, why you live alone, and why night after night, you sit by your computer.
mp-iexpectation calculates expectation values of triangular (Schur) MPO's. The result is expressed in the form of a polynomial in the lattice size, which is asymptotically exact. Currently, the operator to evaluate is hard-coded into the code, so there is not much useful documentation that can be provided here.