1. A method of crawling a graphical user interface (GUI) based application, the method comprising: performing a first-time crawl of a first sequence of actions of a graphical user interface (GUI) based application, the first-time crawl being a first time that the first sequence of actions is crawled, the first sequence of actions being a prefix of a second sequence of actions that includes one or more additional actions than the first sequence of actions; extending the first-time crawl by the one or more additional actions such that the second sequence of actions is crawled during the first-time crawl determining a first input/output sequence associated with the first sequence of actions based on the first-time crawl; and determining a second input/output sequence associated with the second sequence of actions based on the first-time crawl.