text: /**
   * Build string from numbers from 1 to n
   * @param {number} input
   * @returns {string} Returns the string from 1 to input.
   */
  function stringBuilder(input) {
  
      //if input argument is not number then finished program
      if (typeof input !== 'number' || isNaN(input)) {
          return;
      }
  
      let str = '';
      //from 1 to n
      if (input >= 1) {
          for (let i = 1; i <= input; i++) {
              i === input ? str += i : str += i + ',';
          }
      }
      //from 1 to -n
      if (input < 1) {
          for (var j = 1; j >= input; j--) {
              j === input ? str += j : str += j + ',';
          }
      }
  
      return str;
  
  };
  
  module.exports = stringBuilder;