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: match_colors_left_right.m
    path of file: ./repos/CanlabCore/CanlabCore/@region
    
    the code of the file until where you have to start completion: function [all_colors, leftmatched, rightmatched, midline, leftunmatched, rightunmatched] = match_colors_left_right(r, varargin)
% Given a region object and optional colorfun, generate a list of colors
% for each region, assigning the same color to symmetric regions in left
% and right hemispheres.
%
% [all_colors, leftmatched, rightmatched, midline, leftunmatched, rightunmatched] = match_colors_left_right(r, varargin)
%
% - input custom color function

    
function [all_colors, leftmatched, rightmatched, midline, leftunmatched, rightunmatched] = match_colors_left_right(r, varargin)
% Given a region object and optional colorfun, generate a list of colors
% for each region, assigning the same color to symmetric regions in left
% and right hemispheres.
%
% [all_colors, leftmatched, rightmatched, midline, leftunmatched, rightunmatched] = match_colors_left_right(r, varargin)
%
% - input custom color function
% [all_colors, leftmatched, rightmatched, midline, leftunmatched, rightunmatched] = match_colors_left_right(r, @(n) custom_colors([1 0 .5], [.5 0 1], n));

colorfun = @scn_standard_colors;

if length(varargin) > 0, colorfun = varargin{1}; end