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: compose.m
    path of file: ./repos/chebfun/@diskfun
    
    the code of the file until where you have to start completion: function f = compose(f, op, varargin)
%COMPOSE   compose command for DISKFUN objects. 

    
function f = compose(f, op, varargin)
%COMPOSE   compose command for DISKFUN objects. 
% 
%   F = COMPOSE(F, OP) returns the DISKFUN that approximates OP(F).
% 
%   F = COMPOSE(F, OP, G) returns the DISKFUN that approximates OP(F, G).
%
%   F = COMPOSE(F, G) with a CHEBFUN G with one column returns a DISKFUN that
%   approximates G(F).  If G has two columns, the result is a DISKFUNV. For a
%   CHEBFUN2 or CHEBFUN2V, the composition is interpreted as G(real(F),
%   imag(F)).
%
% This command is a wrapper for the DISKFUN constructor. 

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

if ( isa(op, 'chebfun') )
    % Composition OP(f) of DISKFUN f and CHEBFUN OP.
    
    if ( length(op.domain) > 2 )
        % If OP has several pieces, OP(DISKFUN) might be inaccurate.
        warning('CHEBFUN:DISKFUN:compose:pieces', ...
            ['The composition of a CHEBFUN with several pieces and a DISKFUN\n', ...
            'might be inaccurate.']);
    end