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: issigned.m
    path of file: ./repos/SuiteSparse/GraphBLAS/GraphBLAS/@GrB
    
    the code of the file until where you have to start completion: function s = issigned (arg)
%GRB.ISSIGNED Determine if a type is signed or unsigned.
% s = GrB.issigned (type) returns true if type is the string 'double',

    
function s = issigned (arg)
%GRB.ISSIGNED Determine if a type is signed or unsigned.
% s = GrB.issigned (type) returns true if type is the string 'double',
% 'single', 'single complex', 'double complex', 'int8', 'int16', 'int32',
% or 'int64'.
%
% s = GrB.issigned (A), where A is a matrix, is the same as
% s = GrB.issigned (GrB.type (A)).
%
% See also GrB/isinteger, GrB/isreal, GrB/isnumeric, GrB/isfloat, GrB.type.

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

if (ischar (arg))
    type = arg ;
elseif (isobject (arg))
    arg = arg.opaque ;
    type = gbtype (arg) ;
else
    type = gbtype (arg) ;
end