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_minbycol.m
    path of file: ./repos/SuiteSparse/GraphBLAS/GraphBLAS/@GrB/private
    
    the code of the file until where you have to start completion: function C = gb_minbycol (op, A)
%GB_MINBYCOL min, by column
% Implements C = min (A, [ ], 1)

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

% C = min (A, [ ], 1) reduces each col to a scalar; C is 1-by-n
desc.in0 = 'transpose' ;
C = gbvreduce (op, A, desc) ;

% if C(j) > 0, but if A(:,j) is sparse, then assign C(j) = 0.
ctype = gbtype (C) ;

    % d (j) = number of entries in A(:,j); d (j) not present if A(:,j) empty
    [m, n] = gbsize (A) ;
    d = gbdegree (A, 'col') ;
    % d (j) is an explicit zero if A(:,j) has 1 to m-1 entries
    d = gbselect (d, '<', int64 (m)) ;
    zero = gbnew (0, ctype) ;

    
function C = gb_minbycol (op, A)
%GB_MINBYCOL min, by column
% Implements C = min (A, [ ], 1)

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

% C = min (A, [ ], 1) reduces each col to a scalar; C is 1-by-n
desc.in0 = 'transpose' ;
C = gbvreduce (op, A, desc) ;

% if C(j) > 0, but if A(:,j) is sparse, then assign C(j) = 0.
ctype = gbtype (C) ;

    % d (j) = number of entries in A(:,j); d (j) not present if A(:,j) empty
    [m, n] = gbsize (A) ;
    d = gbdegree (A, 'col') ;
    % d (j) is an explicit zero if A(:,j) has 1 to m-1 entries
    d = gbselect (d, '<', int64 (m)) ;
    zero = gbnew (0, ctype) ;
    if (gbnvals (d) == n)
        % all columns A(:,j) have between 1 and m-1 entries
        C = gbapply2 (op, C, zero) ;
    else
        d = gbapply2 (['2nd.' ctype], d, zero) ;
        % if d (j) is between 1 and m-1 and C (j) > 0 then C (j) = 0
        C = gbeadd (op, C, d) ;
    end