code: def update_polygon(tri):
      if tri == -1:
          points = [0, 0, 0]
      else:
          points = triang.triangles[tri]
      xs = triang.x[points]
      ys = triang.y[points]
      polygon.set_xy(np.column_stack([xs, ys]))
  
imports: import matplotlib.pyplot
  import numpy
  from matplotlib.patches import Polygon
  from matplotlib.tri import Triangulation
label_desc: Use image node_id 1 for calling a global function with example usage: update_polygon(tri) without return types