code: def load(self, filename):
          '''load waypoints from a file.
          returns number of waypoints loaded'''
          f = open(filename, mode='r')
          version_line = f.readline().strip()
          if version_line == "QGC WPL 100":
              readfn = self._read_waypoints_v100
          elif version_line == "QGC WPL 110":
              readfn = self._read_waypoints_v110
          elif version_line == "QGC WPL PB 110":
              readfn = self._read_waypoints_pb_110
          else:
              f.close()
              raise MAVWPError("Unsupported waypoint format '%s'" % version_line)
  
          self.clear()
          readfn(f)
          f.close()
  
          return len(self.wpointsf load(self, filename):
          '''load waypoints from a file.
          returns number of waypoints loaded'''
          f = open(filename, mode='r')
          version_line = f.readline().strip()
          if version_line == "QGC WPL 100":
              readfn = self._read_waypoints_v100
          elif version_line == "QGC WPL 110":
              readfn = self._read_waypoints_v110
          elif version_line == "QGC WPL PB 110":
              readfn = self._read_waypoints_pb_110
          else:
              f.close()
              raise MAVWPError("Unsupported waypoint format '%s'" % version_line)
  
          self.clear()
          readfn(f)
          f.close()
  
          return len(self.wpoints)
docs: load waypoints from a file.
          returns number of waypoints loaded