text: 'use strict';
  
  exports.isInteger = num => {
    if (typeof num === 'number') {
      return Number.isInteger(num);
    }
    if (typeof num === 'string' && num.trim() !== '') {
      return Number.isInteger(Number(num));
    }
    return false;
  };
  
  /**
   * Find a node of the given type
   */
  
  exports.find = (node, type) => node.nodes.find(node => node.type === type);
  
  /**
   * Find a node of the given type
   */
  
  exports.exceedsLimit = (min, max, step = 1, limit) => {
    if (limit === false) return false;
    if (!exports.isInteger(min) || !exports.isInteger(max)) return false;
    return ((Number(max) - Number(min)) / Number(step)) >= limit;
  };
  
  /**
   * Escape the given node with '\\' before node.value
   */
  
  exports.escapeNode = (block, n = 0, type) => {
    let node = block.nodes[n];
    if (!node) return;
  
    if ((type && node.type === type) || node.type === 'open' || node.type === 'close') {
      if (node.escaped !== true) {
        node.value = '\\' + node.value;
        node.escaped = true;
      }
    }
  };
  
  /**
   * Returns true if the given brace node should be enclosed in literal braces
   */
  
  exports.encloseBrace = node => {
    if (node.type !== 'brace') return false;
    if ((node.commas >> 0 + node.ranges >> 0) === 0) {
      node.invalid = true;
      return true;
    }
    return false;
  };
  
  /**
   * Returns true if a brace node is invalid.
   */
  
  exports.isInvalidBrace = block => {
    if (block.type !== 'brace') return false;
    if (block.invalid === true || block.dollar) return true;
    if ((block.commas >> 0 + block.ranges >> 0) === 0) {
      block.invalid = true;
      return true;
    }
    if (block.open !== true || block.close !== true) {
      block.invalid = true;
      return true;
    }
    return false;
  };
  
  /**
   * Returns true if a node is an open or close node
   */
  
  exports.isOpenOrClose = node => {
    if (node.type === 'open' || node.type === 'close') {
      return true;
    }
    return node.open === true || node.close === true;
  };
  
  /**
   * Reduce an array of text nodes.
   */
  
  exports.reduce = nodes => nodes.reduce((acc, node) => {
    if (node.type === 'text') acc.push(node.value);
    if (node.type === 'range') node.type = 'text';
    return acc;
  }, []);
  
  /**
   * Flatten an array
   */
  
  exports.flatten = (...args) => {
    const result = [];
    const flat = arr => {
      for (let i = 0; i < arr.length; i++) {
        let ele = arr[i];
        Array.isArray(ele) ? flat(ele, result) : ele !== void 0 && result.push(ele);
      }
      return result;
    };
    flat(args);
    return result;
  };
  