Null Sequence in Exponential Sequence

Theorem
Let $(a_n)_{n \in \N} \in \C$ be a sequence of complex numbers such that:
 * $\displaystyle \lim_{n \to +\infty}a_n = 0$

Then:
 * $\displaystyle \lim_{n \to +\infty} \left(1 + \frac {a_n} n\right)^n = 1$