A worker tends to the lawn on the roof of Twitter headquarters in San Francisco, California October 4, 2013. Twitter Inc, racing toward the largest Silicon Valley IPO since Facebook Inc's 2012 coming-out party, hopes to woo investors with rip-roaring revenue growth despite having posted big losses over the past three years. The eight-year-old online messaging service gave potential investors their first glance at its financials on Thursday when it publicly filed its IPO documents, setting the stage for one of the most-anticipated debuts in over a year. REUTERS/Robert Galbraith (UNITED STATES - Tags: SCIENCE TECHNOLOGY BUSINESS)