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: tt_subscheck.m
    path of file: ./repos/imtsl/libs/tensor_toolbox_2.5
    
    the code of the file until where you have to start completion: function ok = tt_subscheck(subs)
%TT_SUBSCHECK Checks for valid subscripts.
%
%  TT_SUBSCHECK(S) throws an error if S is not a valid subscript
%  array, which means that S is a matrix of real-valued, finite,
%  positive, integer subscripts.
%
%  X = TT_SUBSCHECK(S) returns true if S is a valid and false
%  otherwise.
%
%  See also TT_SIZECHECK, TT_VALSCHECK.
%
%MATLAB Tensor Toolbox.
%Copyright 2012, Sandia Corporation.

% This is the MATLAB Tensor Toolbox by T. Kolda, B. Bader, and others.
% http://www.sandia.gov/~tgkolda/TensorToolbox.
% Copyright (2012) Sandia Corporation. Under the terms of Contract
% DE-AC04-94AL85000, there is a non-exclusive license for use of this
% work by or on behalf of the U.S. Government. Export of this data may
% require a license from the United States Government.
% The full license terms can be found in the file LICENSE.txt

%

    
function ok = tt_subscheck(subs)
%TT_SUBSCHECK Checks for valid subscripts.
%
%  TT_SUBSCHECK(S) throws an error if S is not a valid subscript
%  array, which means that S is a matrix of real-valued, finite,
%  positive, integer subscripts.
%
%  X = TT_SUBSCHECK(S) returns true if S is a valid and false
%  otherwise.
%
%  See also TT_SIZECHECK, TT_VALSCHECK.
%
%MATLAB Tensor Toolbox.
%Copyright 2012, Sandia Corporation.

% This is the MATLAB Tensor Toolbox by T. Kolda, B. Bader, and others.
% http://www.sandia.gov/~tgkolda/TensorToolbox.
% Copyright (2012) Sandia Corporation. Under the terms of Contract
% DE-AC04-94AL85000, there is a non-exclusive license for use of this
% work by or on behalf of the U.S. Government. Export of this data may
% require a license from the United States Government.
% The full license terms can be found in the file LICENSE.txt

%
% Includes improvements offered by Marcus Brubaker.

if isempty(subs)
    ok = true;
elseif ndims(subs) == 2 && isreal(subs) ...
        && all(isfinite(subs(:)) & subs(:) > 0) ...
        && isequal(subs,round(subs)) 
    ok = true;
else
    ok = false;
end