docs: def feed(self):
          "Feed a line from the contents of the GPS log to the daemon."
          line = self.testload.sentences[self.index % len(self.testload.sentences)]
          if "%Delay:" in line:
              # Delay specified number of seconds
              delay = line.split()[1]
              time.sleep(int(delay))
          # self.write has to be set by the derived class
          self.write(line)
          if self.progress:
              self.progress("gpsfake: %s feeds %d=%s\n" % (self.testload.name, len(line), repr(line)))
          time.sleep(WRITE_PAD)
          self.index += 1