It is in the mycgimagic.m file at the end

function x=qs2struct(qs)
% return the query string as a structure
% each field is a paramter name
% the value of the field is its value as a string

% an example query string:
% myinput=test&size=2&num=10

% get the indeces of the characters that divide names and fields
div = [0,strfind(qs,'&'),length(qs)+1];
eq = strfind(qs,'=');

x.querystring = qs;
for i=1:length(eq)
    field = qs(div(i)+1:eq(i)-1); %field string
    value = qs(eq(i)+1:div(i+1)-1); %value stirng
    x = setfield(x,field,value); %place in structure
end
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