code: def vol(poly1, poly2):
      volume of a zone defined by two polygon bases """
      c_point = central_p(poly1, poly2)
      c_point = (c_point[0], c_point[1], c_point[2])
      vol_therah = 0
      num = len(poly1)
      poly1.append(poly1[0])
      poly2.append(poly2[0])
      for i in range(num - 2):
          # the upper part
          tehrahedron = [c_point, poly1[0], poly1[i+1], poly1[i+2]]
          vol_therah += vol_tehrahedron(tehrahedron)
          # the bottom part
          tehrahedron = [c_point, poly2[0], poly2[i+1], poly2[i+2]]
          vol_therah += vol_tehrahedron(tehrahedron)
      # the middle part
      for i in range(num):
          tehrahedron = [c_point, poly1[i], poly2[i], poly2[i+1]]
          vol_therah += vol_tehrahedron(tehrahedron)
          tehrahedron = [c_point, poly1[i], poly1[i+1], poly2[i]]
          vol_therah += vol_tehrahedron(tehrahedron)
      return vol_therah
docs: volume of a zone defined by two polygon bases