code: function parseInput(input) {
    var match = re.exec(input);
  
    if (match !== null) {
      var _match = _slicedToArray(match, 6),
          pre_keyword = _match[1],
          operator_keyword = _match[2],
          value = _match[3],
          unit = _match[4],
          post_keyword = _match[5];
  
      if (pre_keyword && post_keyword || pre_keyword && operator_keyword || post_keyword && operator_keyword) {
        return null;
      }
  
      return {
        value: sanitizeValue({
          value: value,
          operator_keyword: operator_keyword,
          post_keyword: post_keyword
        }),
        unit: unit
      };
    }
  
    return null;
  }
docs: Parses value and unit from human-readable relative time.
  @param {string} input
  @return {parsed_input | null} Returns `null` if input can not be parsed.