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: test_threecomponents.m
    path of file: ./repos/chebfun/tests/chebfun3v
    
    the code of the file until where you have to start completion: function pass = test_threecomponents(pref)

    
function pass = test_threecomponents(pref)
% Check whether Chebfun3v works properly with three components.

% Testing chebfun3v objects with three components. 
if ( nargin < 1 ) 
    pref = chebfunpref; 
end