Compact Subsets of T3 Spaces

Theorem
Let $T = \left({X, \vartheta}\right)$ be a $T_3$ space.

Let $A \subseteq X$ be compact in $T$.

Then for each $U \in \vartheta$ such that $A \subseteq U$:
 * $\exists V \in \vartheta: A \subseteq V \subseteq V^- \subseteq U$

where $V^-$ denotes the closure of $V$.