Function GrB_Matrix_assign 

pub unsafe extern "C" fn GrB_Matrix_assign(
    C: GrB_Matrix,
    Mask: GrB_Matrix,
    accum: GrB_BinaryOp,
    A: GrB_Matrix,
    I: *const GrB_Index,
    ni: GrB_Index,
    J: *const GrB_Index,
    nj: GrB_Index,
    desc: GrB_Descriptor,
) -> GrB_Info