code: def find(self, location):
          
          try:
              content = self.store[location]
              return StringIO(content)
          except:
              reason = 'location "%s" not in document store' % location
              raise Exception, reason
docs: Find the specified location in the store.
          @param location: The I{location} part of a URL.
          @type location: str
          @return: An input stream to the document.
          @rtype: StringIO