Given an ideal `I` representing a projective variety `X` in `P^r`, a positive integer k<r, and optionally a ring `GR` with (exactly) `r+1` choose `k+1` variables, representing the ambient space of the Grassmannian of k-planes in `P^r`, this routine returns the ideal in `GR` of the Fano scheme that parametrizes the k-planes lying on `X`. If the optional third argument is not present, the routine fabricates its own ring, and returns an ideal in it.

- Fano(ZZ,Ideal,Ring) -- Fano scheme