You will be given a function f and an output in the form f(??) == output. Your task is to find any input such that executing f on the input leads to the given output. There may be multiple answers, but only output one. First, think step by step. You MUST surround the answer with [ANSWER] and [/ANSWER] tags. Express your answer as a passing assertion containing the input and the given output.

[PYTHON]
def f(x):
    return x + 1
assert f(??) == 17
[/PYTHON]
[THOUGHT]
To find an input such that executing f on the input leads to the given output, we can work backwards from the given assertion. We know that f(??) == 17. 

Since the function f(x) returns x + 1, for f(??) to be equal to 17, the value of ?? should be 16. 
[/THOUGHT]
[ANSWER]
assert f(16) == 17
[/ANSWER]

[PYTHON]
{code}
assert f(??) == {output}
[/PYTHON]
[THOUGHT]
