my_replace.

def my_replace(string, replace):
   new = ''
   i = 0
   while (i < len(string)):
      if (i < len(replace)):
         new = new + replace[i]
      elif (i >= len(replace)):
         new = new + string[i]
      i = i+1
   return new

def setup():
   string = 'thailand'
   replace = 'blue'
   print("Old world is", string, "and New world is", my_replace(string, replace))
   assert my_replace(string, replace) == 'blueland'

setup()