Bounded Above Subset of Real Numbers/Examples/Closed Interval from 0 to 1

Examples of Bounded Above Subset of Real Numbers
Let $I$ be the closed real interval defined as:
 * $I := \openint 0 1$

Then $I$ is bounded above by, for example, $1$, $2$ and $3$, of which $1$ is the supremum.

$I$ is also the greatest element of $I$.