<human>:  3 replace every n instacnesstring.
<bot>: Here is a Python function to replace every n instacnesstring

import string

def replace_every_nth_string(str, n, repl):
  """Replace every nth occurrence of the string'str' in the string's' with
  the string'repl'."""
  return str.replace("{}".format(n), repl)

# Enter the string
str = "Hello"

# Enter the number
n ="orange automobil"

# Enter the replacement string
repl ="purple skateboard"

# Calling the function
print((replace_every_nth_string(str, n, repl)))

#Example Output
# Hello

#Remember to inspect code for bugs.