Loops through the addresses, collapsing concurrent netblocks.

    Example:

        ip1 = IPv4Network('192.0.2.0/26')
        ip2 = IPv4Network('192.0.2.64/26')
        ip3 = IPv4Network('192.0.2.128/26')
        ip4 = IPv4Network('192.0.2.192/26')

        _collapse_addresses_recursive([ip1, ip2, ip3, ip4]) ->
          [IPv4Network('192.0.2.0/24')]

        This shouldn't be called directly; it is called via
          collapse_addresses([]).

    Args:
        addresses: A list of IPv4Network's or IPv6Network's

    Returns:
        A list of IPv4Network's or IPv6Network's depending on what we were
        passed.

def _collapse_addresses_recursive(addresses):
    """Loops through the addresses, collapsing concurrent netblocks.

    Example:

        ip1 = IPv4Network('192.0.2.0/26')
        ip2 = IPv4Network('192.0.2.64/26')
        ip3 = IPv4Network('192.0.2.128/26')
        ip4 = IPv4Network('192.0.2.192/26')

        _collapse_addresses_recursive([ip1, ip2, ip3, ip4]) ->
          [IPv4Network('192.0.2.0/24')]

        This shouldn't be called directly; it is called via
          collapse_addresses([]).

    Args:
        addresses: A list of IPv4Network's or IPv6Network's

    Returns:
        A list of IPv4Network's or IPv6Network's depending on what we were
        passed.

    """
    while True:
        last_addr = None
        ret_array = []
        optimized = False

        for cur_addr in addresses:
            if not ret_array:
                last_addr = cur_addr
                ret_array.append(cur_addr)
            elif (cur_addr.network_address >= last_addr.network_address and
                cur_addr.broadcast_address <= last_addr.broadcast_address):
                optimized = True
            elif cur_addr == list(last_addr.supernet().subnets())[1]:
                ret_array[-1] = last_addr = last_addr.supernet()
                optimized = True
            else:
                last_addr = cur_addr
                ret_array.append(cur_addr)

        addresses = ret_array
        if not optimized:
            return addresses