constructor(
		tokens,
		comments,
		indexMap,
		startLoc,
		endLoc,
		beforeCount,
		afterCount,
	) {
		super(tokens, comments, indexMap, startLoc, endLoc);
		this.index = Math.max(0, this.index - beforeCount);
		this.indexEnd = Math.min(tokens.length - 1, this.indexEnd + afterCount);
	}
Initializes this cursor.
@param {Token[]} tokens The array of tokens.
@param {Comment[]} comments The array of comments.
@param {Object} indexMap The map from locations to indices in `tokens`.
@param {number} startLoc The start location of the iteration range.
@param {number} endLoc The end location of the iteration range.
@param {number} beforeCount The number of tokens this cursor iterates before start.
@param {number} afterCount The number of tokens this cursor iterates after end.