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: feval.m
    path of file: ./repos/chebfun/@linop
    
    the code of the file until where you have to start completion: function M = feval(L, n, flag)

    
function M = feval(L, n, flag)
%FEVAL    Deprecated function, provided for limited backward compatibility.

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

warning('CHEBFUN:LINOP:feval:deprecated',...
    ['This function is provided only for limited backward compatibility.',...
    ' Use MATRIX instead.'] );
warning('off', 'CHEBFUN:LINOP:feval:deprecated')

if ( prod(size(L)) > 1 ) %#ok<PSIZE>
    error('CHEBFUN:LINOP:feval:multivariable', ...
        'This syntax is not available for multivariable systems.')
end