code: def set_data(self, pos=None, color=None):
          
          if pos is not None:
              pos = float(pos)
              xy = self._pos
              if self._is_vertical:
                  xy[0, 0] = pos
                  xy[0, 1] = -1
                  xy[1, 0] = pos
                  xy[1, 1] = 1
              else:
                  xy[0, 0] = -1
                  xy[0, 1] = pos
                  xy[1, 0] = 1
                  xy[1, 1] = pos
              self._changed['pos'] = True
  
          if color is not None:
              color = np.array(color, dtype=np.float32)
              if color.ndim != 1 or color.shape[0] != 4:
                  raise ValueError('color must be a 4 element float rgba tuple,'
                                   ' list or array')
              self._color = color
              self._changed['color'] = True
docs: Set the data
  
          Parameters
          ----------
          pos : float
              Position of the line along the axis.
          color : list, tuple, or array
              The color to use when drawing the line. If an array is given, it
              must be of shape (1, 4) and provide one rgba color per vertex.