function checkSpacingForFunction(node) {
			const firstToken = node && sourceCode.getFirstToken(node);

			if (
				firstToken &&
				((firstToken.type === "Keyword" &&
					firstToken.value === "function") ||
					firstToken.value === "async")
			) {
				checkSpacingBefore(firstToken);
			}
		}
Reports `async` or `function` keywords of a given node if usage of
spacing around those keywords is invalid.
@param {ASTNode} node A node to report.
@returns {void}