code: def tree(plist, l, a, f):
      """plist is list of pens
      l is length of branch
      a is half of the angle between 2 branches
      f is factor by which branch is shortened
      from level to level."""
      if l > 3:
          lst = []
          for p in plist:
              p.forward(l)
              q = p.clone()
              p.left(a)
              q.right(a)
              lst.append(p)
              lst.append(q)
          for x in tree(lst, l * f, a, f):
              yield None
  
imports: from turtle import Turtle, mainloop
  from time import perf_counter
label_desc: Use image node_id 1 for calling a global function with example usage: tree(plist, l, a, f) without return types