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: fitMeanMSD.m
    path of file: ./repos/msdanalyzer/@msdanalyzer
    
    the code of the file until where you have to start completion: function  varargout = fitMeanMSD(obj, clip_factor)
%%FITMEANMSD Fit the weighted averaged MSD by a linear function.

    
function  varargout = fitMeanMSD(obj, clip_factor)
%%FITMEANMSD Fit the weighted averaged MSD by a linear function.
%
% obj.fitMeanMSD computes and fits the weighted mean MSD by a
% straight line y = a * x. The fit is therefore valid only for
% purely diffusive behavior. Fit results are displayed in the
% command window.
%
% obj.fitMeanMSD(clip_factor) does the fit, taking into account
% only the first potion of the average MSD curve specified by
% 'clip_factor' (a double between 0 and 1). If the value
% exceeds 1, then the clip factor is understood to be the
% maximal number of point to take into account in the fit. By
% default, it is set to 0.25.
%
% [fo, gof] = obj.fitMeanMSD(...) returns the fit object and the
% goodness of fit.

if nargin < 2
    clip_factor = 0.25;
end