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: signup.m
    path of file: ./repos/plotly_matlab/plotly/plotly_user_aux
    
    the code of the file until where you have to start completion: function response = signup(username, email)
% SIGNUP(username, email)  Remote signup to plot.ly and plot.ly API
%     response = signup(username, email) makes an account on plotly and returns a temporary password and an api key
%
% See also plotly, plotlylayout, plotlystyle, signin
%

    
function response = signup(username, email)
% SIGNUP(username, email)  Remote signup to plot.ly and plot.ly API
%     response = signup(username, email) makes an account on plotly and returns a temporary password and an api key
%
% See also plotly, plotlylayout, plotlystyle, signin
%
% For full documentation and examples, see https://plot.ly/api
    platform = 'MATLAB';
    payload = {'version', '0.2', 'un', username, 'email', email,'platform',platform};
    url = 'https://plot.ly/apimkacct';
    resp = urlread(url, 'Post', payload);
    response = loadjson(resp);

    f = fieldnames(response);
    if any(strcmp(f,'error'))
        error(response.error)
    end