Check whether a value is defined (non-nullable), meaning it is neither `null` or `undefined`. This can be useful as a type guard, as for example, `[1, null].filter(Boolean)` does not always type-guard correctly.

The problem is, algorithms were never designed to handle such tough choices. They are built to pursue a single mathematical goal, such as maximizing the number of soldiers’ lives saved or minimizing the number of civilian deaths. When you start dealing with multiple, often competing, objectives or try to account for intangibles like “freedom” and “well-being,” a satisfactory mathematical solution doesn’t always exist.