My Derivative Is Myself

Calculus Level 1

How many functions are there such that \(f(x) = f'(x)\)?

Clarification: While functions such as \(f(x)=2^{x}\) and \(f(x)=2^{x+1}\) are in the same family of functions, they are different functions, so if you found those two as the only answers, your answer would be 2.