Sequence Converges to Within Half Limit/Complex Numbers

Theorem
Let $\sequence {z_n}$ be a sequence in $\C$.

Let $\sequence {z_n}$ be convergent to the limit $l$.

That is, let $\ds \lim_{n \mathop \to \infty} z_n = l$ where $l \ne 0$.

Then:
 * $\exists N: \forall n > N: \cmod {z_n} > \dfrac {\cmod l} 2$

Proof
Suppose $l > 0$.

Let us choose $N$ such that:
 * $\forall n > N: \cmod {z_n - l} < \dfrac {\cmod l} 2$

Then: