code: def valid_ovsdb_addr(addr):
      
      # Assumes Unix socket format: "unix:file"
      m = re.match(r'unix:(\S+)', addr)
      if m:
          file = m.group(1)
          return os.path.isfile(file)
      # Assumes TCP/SSL socket format: "tcp:ip:port" or "ssl:ip:port"
      m = re.match(r'(tcp|ssl):(\S+):(\d+)', addr)
      if m:
          address = m.group(2)
          port = m.group(3)
          if '[' in address:
              address = address.strip('[').strip(']')
              return ip.valid_ipv6(address) and port.isdigit()
          else:
              return ip.valid_ipv4(address) and port.isdigit()
      # Assumes invalid format or unsupported type
      return False
docs: Returns True if the given addr is valid OVSDB server address, otherwise
      False.
  
      The valid formats are:
  
      - ``unix:file``
      - ``tcp:ip:port``
      - ``ssl:ip:port``
  
      If ip is IPv6 address, wrap ip with brackets (e.g., ssl:[::1]:6640).
  
      :param addr: str value of OVSDB server address.
      :return: True if valid, otherwise False.