function isLoop(node) {
	return Boolean(node && anyLoopPattern.test(node.type));
}
Checks whether a given node is a loop node or not.
The following types are loop nodes:

- DoWhileStatement
- ForInStatement
- ForOfStatement
- ForStatement
- WhileStatement
@param {ASTNode|null} node A node to check.
@returns {boolean} `true` if the node is a loop node.