input: Write a python function to generate a password by appending the index of each character in the string to the end of the string.
  assert generate_password("Hello") == "Hello01234"
  assert generate_password("Python") == "Python012345"
  assert generate_password("Test") == "Test0123"
output: def generate_password(s):
      return s + ''.join(str(i) for i in range(len(s)))