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: isSubset.m
    path of file: ./repos/chebfun
    
    the code of the file until where you have to start completion: function out = isSubset(A, B, tol)
%ISSUBSET   Test if A is a subset of B.
%   OUT = ISSUBSET(A, B, TOL) returns logical true if A is a subset of B up

    
function out = isSubset(A, B, tol)
%ISSUBSET   Test if A is a subset of B.
%   OUT = ISSUBSET(A, B, TOL) returns logical true if A is a subset of B up
%   to the tolerance TOL, where A and B are domains of a chebfun, chebfun2 
%   or chebfun3 (i.e., vectors of size 1x2, 1x4 or 1x6 with A(1) <= A(2), 
%   A(3) <= A(4), A(5) <= A(6)).

% Copyright 2017 by The University of Oxford and The Chebfun Developers.
% See http://www.chebfun.org/ for Chebfun information.

if ( isempty(A) )
    out = 1;
    return
end