code: def layout_circle(self):
      '''Position vertices evenly around a circle.'''
      n = self.num_vertices()
      t = np.linspace(0, 2*np.pi, n+1)[:n]
      return np.column_stack((np.cos(t), np.sin(t))f layout_circle(self):
      '''Position vertices evenly around a circle.'''
      n = self.num_vertices()
      t = np.linspace(0, 2*np.pi, n+1)[:n]
      return np.column_stack((np.cos(t), np.sin(t)))
docs: Position vertices evenly around a circle.