code: def calcCubicParameters(pt1, pt2, pt3, pt4):
      x2, y2 = pt2
      x3, y3 = pt3
      x4, y4 = pt4
      dx, dy = pt1
      cx = (x2 - dx) * 3.0
      cy = (y2 - dy) * 3.0
      bx = (x3 - x2) * 3.0 - cx
      by = (y3 - y2) * 3.0 - cy
      ax = x4 - dx - cx - bx
      ay = y4 - dy - cy - by
      return (ax, ay), (bx, by), (cx, cy), (dx, dy)
  
imports: from fontTools.misc.arrayTools import calcBounds, sectRect, rectArea
  from fontTools.misc.transform import Identity
  import math
  from collections import namedtuple
  from math import sqrt, acos, cos, pi
label_desc: Use image node_id 28 for calling a global function with example usage: calcCubicParameters(pt1, pt2, pt3, pt4) and returns: ax,  ay,  bx,  by,  cx,  cy,  dx,  dy