Function GrB_mxm 

pub unsafe extern "C" fn GrB_mxm(
    C: GrB_Matrix,
    Mask: GrB_Matrix,
    accum: GrB_BinaryOp,
    semiring: GrB_Semiring,
    A: GrB_Matrix,
    B: GrB_Matrix,
    desc: GrB_Descriptor,
) -> GrB_Info