code: function _isQuote(c, escape, quote) {
          if (escape === "\\") {
              return false;
          }
          if (quote !== undefined) {
              return c === quote;
          }
          return c === "\"" || c === "'";
      }
docs: Test if the given character is a quote character
  {char} source character
  {char} escape (previous) character
  {char} quote character