code: function (line) {
              if (this._content) {
                  this._content = this._content + this._newLine + line;
              } else {
                  this._values = [];
                  this._content = line;
              }
              return this._parseContent();
          }
docs: If some content remains from previous parsing, concatenate it and parse
  
  @param {String} line CSV line
  @return {String[]|undefined} Resulting values or undefined if not yet finalized
  @since 0.2.3