Returns True if `address` is a valid IPv4 address.
    
        >>> validipaddr('192.168.1.1')
        True
        >>> validipaddr('192.168.1.800')
        False
        >>> validipaddr('192.168.1')
        False

def validipaddr(address):
    """
    Returns True if `address` is a valid IPv4 address.
    
        >>> validipaddr('192.168.1.1')
        True
        >>> validipaddr('192.168.1.800')
        False
        >>> validipaddr('192.168.1')
        False
    """
    try:
        octets = address.split('.')
        if len(octets) != 4:
            return False
        for x in octets:
            if not (0 <= int(x) <= 255):
                return False
    except ValueError:
        return False
    return True