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: subsref.m
    path of file: ./repos/chebfun/@chebfun3v
    
    the code of the file until where you have to start completion: function varargout = subsref(F, ref)
%SUBSREF   CHEBFUN3V subsref.
%   F(X, Y, Z) returns the values of the CHEBFUN3V object F evaluated on the
%   array (X, Y, Z).
%
%   F(k) returns the first component of the chebfun3v object F if k=1, the
%   second if k=2, and the third if k=3.
%
%   F(G) where G is a CHEBFUN3V returns the CHEBFUN3V representing the
%   composition F(G).  If G is a CHEBFUN2V, then F(G) is a CHEBFUN2V.  If G is a
%   CHEBFUN with three columns, then F(G) is a CHEBFUN.  If G is a SPHEREFUNV,
%   then F(G) is a SPHEREFUNV.
%
%   F(X, Y, Z) where X, Y, Z are CHEBFUN3 objects is a CHEBFUN3V representing
%   the composition.  Similarly if X, Y, Z are CHEBFUN or CHEBFUN2 objects.

    
function varargout = subsref(F, ref)
%SUBSREF   CHEBFUN3V subsref.
%   F(X, Y, Z) returns the values of the CHEBFUN3V object F evaluated on the
%   array (X, Y, Z).
%
%   F(k) returns the first component of the chebfun3v object F if k=1, the
%   second if k=2, and the third if k=3.
%
%   F(G) where G is a CHEBFUN3V returns the CHEBFUN3V representing the
%   composition F(G).  If G is a CHEBFUN2V, then F(G) is a CHEBFUN2V.  If G is a
%   CHEBFUN with three columns, then F(G) is a CHEBFUN.  If G is a SPHEREFUNV,
%   then F(G) is a SPHEREFUNV.
%
%   F(X, Y, Z) where X, Y, Z are CHEBFUN3 objects is a CHEBFUN3V representing
%   the composition.  Similarly if X, Y, Z are CHEBFUN or CHEBFUN2 objects.
%
%   F.PROP returns the property PROP of F as defined by GET(F,'PROP').
%   Throws an error.

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

% check for empty CHEBFUN3V object.
if ( isempty(F) )
    varargout = {[]};
    return
end