python - Make function recursive -

i trying convert function below recursive 1 keep getting error when try it.

typeerror: unsupported operand type(s) *: 'float' , 'nonetype'

def turtle_spiral(forward):      minus = 8      t = turtle.turtle()      t.pendown()      t.shape("turtle")     #while forward > 10:      randm = random.randrange(5)     colours = ["blue", "orange", "yellow", "green",   "purple","black","red","pink"]      t.goto(-100,0)      if forward <= 10:         return false      else:         t.color(colours[randm])         #t.speed(10)         t.fd(turtle_spiral(forward*minus))         #t.circle(forward, 360)         t.right(90)         #forward -= minus   turtle_spiral(100)  wd.mainloop() 

i've had go @ modifying code think want do:

import turtle import random  def turtle_spiral(forward):      minus = 8     randm = random.randrange(5)     colours = ["blue", "orange", "yellow", "green",   "purple","black","red","pink"]      if forward <= 10:         return 0     else:         t.color(colours[randm])         t.right(90)         t.fd(forward)         return turtle_spiral(forward-minus)  t = turtle.turtle()  t.pendown()  t.shape("turtle") turtle_spiral(100) 

the key recursion defining end point(s) of recursion. in case, when turtle being asked go forward distance of less 10. @ end point recursive function should not call , return.

in other cases want function call @ point argument gets closer towards end-point. in case argument forward-minus , value closer , closer end condition more turtle_spiral calls recursively.