new_contents: import socket
  
  
  def is_ipv6(address):
      """
      Check if an address is an IPV6 one, but trim commonly used brackets as the
      ``socket`` module complains about them.
      """
      if not isinstance(address, str):
          return False
  
      if address.startswith('['):  # assume we need to split on possible port
          address = address.split(']:')[0]
      # strip leading/trailing brackets so inet_pton understands the address
      address = address.strip('[]')
      try:
          socket.inet_pton(socket.AF_INET6, address)
      except socket.error:  # not a valid address
          return False
      return True
  
subject: add a network utility to check for ipv6