function normalizeFixes(descriptor, sourceCode) {
	if (typeof descriptor.fix !== "function") {
		return null;
	}

	const ruleFixer = new RuleFixer({ sourceCode });

	// @type {null | Fix | Fix[] | IterableIterator<Fix>}
	const fix = descriptor.fix(ruleFixer);

	// Merge to one.
	if (fix && Symbol.iterator in fix) {
		return mergeFixes(Array.from(fix), sourceCode);
	}

	assertValidFix(fix);
	return cloneFix(fix);
}
Gets one fix object from the given descriptor.
If the descriptor retrieves multiple fixes, this merges those to one.
@param {MessageDescriptor} descriptor The report descriptor.
@param {SourceCode} sourceCode The source code object to get text between fixes.
@returns {({text: string, range: number[]}|null)} The fix for the descriptor