mechanize could not retrieve all forms(including some generated by js)
Launch Firefox, use HTTP Live Headers to inspect what the javascript does, then imitate that using Mechanize / relevant HTTP requests.
it is a html including two forms. One of them is generated dynamic by js when the page is loaded
So, if I try to fetch them, only one form could be return, and the form generated dynamic not found. 
the question is
how to fetch all forms even if they are generated by js.