code: function extractKeyValue (line) {
    var kv = {
      key: undefined,
      value: undefined,
    };
  
    var matches = kvRE.exec(line);
    if (matches !== null && matches.length === 3) {
      kv.key = matches[1];
      kv.value = matches[2];
    }
  
    return kv;
  }
docs: Uses a regular expression to extract a key
  and value from the line.
  
  @param {string} line
  @returns {{key: undefined, value: undefined}}