src/vs/editor/common/tokens/contiguousTokensEditing.ts/ContiguousTokensEditing/insert
class ContiguousTokensEditing:	public static insert(lineTokens: Uint32Array | ArrayBuffer | null, chIndex: number, textLength: number): Uint32Array | ArrayBuffer | null {
		if (lineTokens === null || lineTokens === EMPTY_LINE_TOKENS) {
			// nothing to do
			return lineTokens;
		}

		const tokens = toUint32Array(lineTokens);
		const tokensCount = (tokens.length >>> 1);

		let fromTokenIndex = LineTokens.findIndexInTokensArray(tokens, chIndex);
		if (fromTokenIndex > 0) {
			const fromTokenStartOffset = tokens[(fromTokenIndex - 1) << 1];
			if (fromTokenStartOffset === chIndex) {
				fromTokenIndex--;
			}
		}
		for (let tokenIndex = fromTokenIndex; tokenIndex < tokensCount; tokenIndex++) {
			tokens[tokenIndex << 1] += textLength;
		}
		return lineTokens;
	}