lib/utils/source-code-utils.js
function(prevNode, currentNode) {
        if (
            prevNode && astUtils.isASTNode(prevNode) &&
			currentNode && astUtils.isASTNode(currentNode) &&
			prevNode.start <= currentNode.start
        ) {
            return this.text.slice(prevNode.end, currentNode.start);
        }

        throw new Error("Invalid argument for one or both nodes");
    }
function(prevNode, currentNode) {
        if (
            prevNode && astUtils.isASTNode(prevNode) &&
			currentNode && astUtils.isASTNode(currentNode) &&
			prevNode.start <= currentNode.start
        ) {
            return this.text.slice(prevNode.end, currentNode.start);
        }

        throw new Error("Invalid argument for one or both nodes");
    }
Get the entire string between 2 nodes - ranging from prevNode.end to currentNode.start (exclusive)
@param {ASTNode} prevNode The 1st AST Node
@param {ASTNode} currentNode The 2nd AST Node
@returns {String} charsBetweenNodes The entire string netween the 2 nodes