src/vs/editor/common/tokens/sparseMultilineTokens.ts/SparseMultilineTokens/split
class SparseMultilineTokens:	public split(range: Range): [SparseMultilineTokens, SparseMultilineTokens] {
		// split tokens to two:
		// a) all the tokens before `range`
		// b) all the tokens after `range`
		const startLineIndex = range.startLineNumber - this._startLineNumber;
		const endLineIndex = range.endLineNumber - this._startLineNumber;

		const [a, b, bDeltaLine] = this._tokens.split(startLineIndex, range.startColumn - 1, endLineIndex, range.endColumn - 1);
		return [new SparseMultilineTokens(this._startLineNumber, a), new SparseMultilineTokens(this._startLineNumber + bDeltaLine, b)];
	}