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: spinop.m
    path of file: ./repos/chebfun/@spinop
    
    the code of the file until where you have to start completion: classdef spinop < spinoperator
%SPINOP   Class for representing 1D differential operators in SPIN.
%   SPINOP is a class for representing the spatial part S of a time-dependent 
%   PDE of the form u_t = S(u) = Lu + N(u) in 1D, where L is a linear 
%   operator and N is a nonlinear operator. 
%
%   S = SPINOP(PDECHAR) creates a SPINOP object S defined by the string PDECHAR.
%   Strings available include 'AC' for Allen-Cahn equation, 'KS' for 
%   Kuramoto
    
function of u that does not involve any derivative of u, 
%           and m is the differentiation order. The following function handles 
%           are allowed:
%
%               N = @(u) .5*diff(u.^2);
%               N = @(u) diff(u.^2 + u.^3, 2);
%               N = @(u) exp(u) + cos(sin(2*u));
%
%           The following function handles are not allowed:
%
%               N = @(u) u.*diff(u); 
%               N = @(u) diff(u.^2, 2) + diff(u.^3, 2);
% 
%           For systems of equations, the nonlinear part has to be of the form 
%           @(u) f(u), i.e., no differentiation.         
%          
% Example 1: To construct a SPINOP corresponding to the KdV equation on 
%            DOM = [-pi pi] x TSPAN = [0 1e-2] with initial condition 
%            u0(x) = 100*sin(x), one can type
%
%            dom = [-pi pi]; tspan = [0 1e-2];
%            S = spinop(dom, tspan);
%            S.lin = @(u) -diff(u,3);
%            S.nonlin = @(u) -.5*diff(u.^2);
%            S.init = chebfun(@(x) 100*sin(x), dom);
%
% See also SPINOPERATOR, SPIN.

% Copyright 2017 by The University of Oxford and The Chebfun Developers.
% See http://www.chebfun.org/ for Chebfun information.
    
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    %% CLASS CONSTRUCTOR:
    %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    methods ( Access = public, Static = false )
        
        function S = spinop(varargin)
            
            % Zero input argument:
            if ( nargin == 0 )
                return
            
            % One input argument:
            elseif ( nargin == 1 )
                if ( isa(varargin{1}, 'char') == 1 )
                    [L, N, dom, tspan, u0] = parseInputs(varargin{1});
                    S.lin = L;
                    S.nonlin = N;
                    S.domain = dom;
                    S.tspan = tspan;
                    S.init = u0;
                else
                    error('SPINOP:constructor', ['When constructing a ', ...
                        'SPINOP with one input argument, this argument ', ...
                        'should be a STRING.'])
                end