code: def validate_cidr(s):
      
      if _CIDR_RE.match(s):
          ip, mask = s.split('/')
          if validate_ip(ip):
              if int(mask) > 128:
                  return False
          else:
              return False
          return True
      return False
docs: Validate a CIDR notation ip address.
  
      The string is considered a valid CIDR address if it consists of a valid
      IPv6 address in hextet format followed by a forward slash (/) and a bit
      mask length (0-128).
  
  
      >>> validate_cidr('::/128')
      True
      >>> validate_cidr('::/0')
      True
      >>> validate_cidr('fc00::/7')
      True
      >>> validate_cidr('::ffff:0:0/96')
      True
      >>> validate_cidr('::')
      False
      >>> validate_cidr('::/129')
      False
      >>> validate_cidr(None) #doctest: +IGNORE_EXCEPTION_DETAIL
      Traceback (most recent call last):
          ...
      TypeError: expected string or buffer
  
  
      :param s: String to validate as a CIDR notation ip address.
      :type s: str
      :returns: ``True`` if a valid CIDR address, ``False`` otherwise.
      :raises: TypeError