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: unormal.m
    path of file: ./repos/chebfun/@spherefunv
    
    the code of the file until where you have to start completion: function N = unormal( dom )
%UNORMAL unit normal vector to the unit sphere.
%   N = UNORMAL( DOM ) returns a SPHEREFUNV representing the unit normal
%   vector to the unit sphere using the spherical coordinate domain
%   specified, i.e. DOM = [-pi -pi 0 pi], for co-latitude.
%
%   N = UNORMAL returns a SPHEREFUNV representing the unit normal
%   vector to the unit sphere, using the default spherical coordinates
%   domain, which is co-latitude.
%

    
function N = unormal( dom )
%UNORMAL unit normal vector to the unit sphere.
%   N = UNORMAL( DOM ) returns a SPHEREFUNV representing the unit normal
%   vector to the unit sphere using the spherical coordinate domain
%   specified, i.e. DOM = [-pi -pi 0 pi], for co-latitude.
%
%   N = UNORMAL returns a SPHEREFUNV representing the unit normal
%   vector to the unit sphere, using the default spherical coordinates
%   domain, which is co-latitude.
%
%   See also SPHEREFUNV/TANGENTIAL, SPHEREFUNV/DOT, SPHEREFUNV/CURL

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


if ~exist( 'dom', 'var' ) || isempty( dom )
    dom = [-pi pi 0 pi];
end