code: def _plot_point_source(self, source, point_marker='ks', point_size=2.0):
          
          x, y = self.m(source.geometry.longitude, source.geometry.latitude)
          self.m.plot(x, y, point_marker, markersize=point_size)
docs: Plots the area source
          :param source:
              Area source as instance of :class: mtkPointSource
          :param str point_marker:
              Marker style for point (see matplotlib documentation for detail)
          :param float marker size for point:
              Line width of border (see matplotlib documentation for detail)