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: normal.m
    path of file: ./repos/chebfun/@spherefunv
    
    the code of the file until where you have to start completion: function N = normal(F)
%NORMAL   Projection onto the normal vector to the unit sphere.
%   N = NORMAL(F) returns a SPHEREFUNV representing the projection of F
%   onto the normal vector to the sphere.
%
% See also SPHEREFUNV/TANGENT, SPHEREFUNV/DOT, SPHEREFUNV/CURL.

% Copyright 2017 by The University of Oxford and The Chebfun Developers.

    
function N = normal(F)
%NORMAL   Projection onto the normal vector to the unit sphere.
%   N = NORMAL(F) returns a SPHEREFUNV representing the projection of F
%   onto the normal vector to the sphere.
%
% See also SPHEREFUNV/TANGENT, SPHEREFUNV/DOT, SPHEREFUNV/CURL.

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

% If F is not a SPHEREFUNV then:
if ( ~isa(F, 'spherefunv') )
    error('SPHEREFUN:SPHEREFUNV:normal:type', 'Input must be a spherefunv.');
end