The colaboratory notebook version of this only has the answer and not the practice problem or test assertions. This is what is in the notebook version: def reverse_string(input): answer = "" # Your code goes here for letter in input: answer = letter + answer # End of your code return answer reverse_string("hola") ----------------------------------------------- This is what is in the correct GitHub version: def reverse_string(input_str): answer = "" # Your code goes here # End of your code return answer # Tests below, do not change assert reverse_string("hello") == "olleh", "Cannot reverse 'hello'" assert reverse_string("") == "", "When given an empty string it returns an empty string, but doesn't" assert reverse_string("racecar") == "racecar", "Cannot reverse 'racecar'" assert reverse_string("12345") == "54321", "Cannot reverse 12345" # If the program gets here, the code works! print("Your solution works!")