You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: GB_spec_subassign.m
    path of file: ./repos/SuiteSparse/GraphBLAS/Test
    
    the code of the file until where you have to start completion: function C = GB_spec_subassign (C, Mask, accum, A, I, J, descriptor, scalar)
%GB_SPEC_SUBASSIGN a mimic of GxB_subassign
%
% Usage:
% C = GB_spec_subassign (C, Mask, accum, A, I, J, descriptor, scalar)
%
% Computes C(I,J)<Mask> = accum(C(I,J),A), in GraphBLAS notation.
%
% This function does the same thing as GxB_Matrix_subassign,
% GxB_Vector_subassign, GxB_Matrix_subassign_TYPE, GxB_Vector_subassign_TYPE,
% GxB_Row_subassign, and GxB_Col_subassign functions.  In all cases, the Mask
% is the same size as A (after optionally being transpose) and the submatrix
% C(I,J).  Entries outside the C(I,J) submatrix are never modified.


    
function C = GB_spec_subassign (C, Mask, accum, A, I, J, descriptor, scalar)
%GB_SPEC_SUBASSIGN a mimic of GxB_subassign
%
% Usage:
% C = GB_spec_subassign (C, Mask, accum, A, I, J, descriptor, scalar)
%
% Computes C(I,J)<Mask> = accum(C(I,J),A), in GraphBLAS notation.
%
% This function does the same thing as GxB_Matrix_subassign,
% GxB_Vector_subassign, GxB_Matrix_subassign_TYPE, GxB_Vector_subassign_TYPE,
% GxB_Row_subassign, and GxB_Col_subassign functions.  In all cases, the Mask
% is the same size as A (after optionally being transpose) and the submatrix
% C(I,J).  Entries outside the C(I,J) submatrix are never modified.

% SuiteSparse:GraphBLAS, Timothy A. Davis, (c) 2017-2023, All Rights Reserved.
% SPDX-License-Identifier: Apache-2.0

%-------------------------------------------------------------------------------
% get inputs
%-------------------------------------------------------------------------------

if (nargout > 1 || nargin ~= 8)
    error ('usage: C = GB_spec_subassign (C, Mask, accum, A, I, J, descriptor, scalar)') ;
end