def number2string(s):
    """ Return string representation of a number.

    Returns as it is, if ValueError is raised.    #this feature not working
    Returns string exponent form for very large numbers.

    >>> number2string(21.3) == '21.3'
    True
    >>> number2string(21) == '21'
    True
    >>> number2string('lol') == 'lol'
    True
    """
    try:
        return '{0:g}'.format(float(s))
    except ValueError:
        return s
