code: function stringQuoteChar(atom) {
    var str = toString(valueOf(atom));
    var quoteChar;
    if(isQuotedString(value)) {
      quoteChar = value.charAt(0);
    }
    return quoteChar;
  }
docs: If atom is a string, which quote character does it use?
  Otherwise returns undefined.
  We support the same string quotes as javascript: ", ', and `