Complex analysis examples and solutions pdf

What is an example of an open set in complex analysis?

If a bubble (circle) can be drawn around a point and the bubble is inside the set then it is called an interior point.
If all the points of a set are interior points, meaning a bubble can be drawn around each and every point of the set, then the set is an open set.
Some examples of open sets are x \x26lt; 5 or y \x26gt; 2 x + 5..