Magnitude of differentiable complex function $f(z)$
I have the question
Let $f(z)$ be an entire function and assuming $f(z)$ does not take values in $|w|\leq 1$, show that $f(z)$ is identically constant.
I tried to prove with Liouville's theorem, but I couldn't find the correct implementation., because I did not understand the meaning of "$f(z)$ does not take values in $|w|\leq1$". Could you help me please? If you can, could you give the proof?