code: def angle(x1, y1, x2, y2):
      
      sign = 1.0
      usign = (x1*y2 - y1*x2)
      if usign < 0:
          sign = -1.0
      num = x1*x2 + y1*y2
      den = hypot(x1,y1) * hypot(x2,y2)
      ratio = min(max(num/den, -1.0), 1.0)
      return sign * degrees(acos(ratio))
docs: The angle in degrees between two vectors.