title: How to get head revision number of a file, or the changelist number when it was checked in / changed
body: <p>I'm writing a python app that connects to perforce on a daily basis. The app gets the contents of an excel file on perfoce, parses it, and copies some data to a database. The file is rather big, so I would like to keep track of which revision of the file the app last read on the database, this way i can check to see if the revision number is higher and avoid reading the file if it has not changed.</p>
  
  <p>I could make do with getting the revision number, or the changelist number when the file was last checked in / changed. Or if you have any other suggestion on how to accomplish my goal of avoiding doing an unnecessary read of the file.</p>
  
  <p>I'm using python 2.7 and the perforce-python API</p>