python check ports

import socket
import errno
import contextlib

reserved_ports = set()

def get_open_port(lowest_port = 0, highest_port = None, bind_address = '', *socket_args, **socket_kwargs):
    if highest_port is None:
        highest_port = lowest_port + 100
    while lowest_port < highest_port:
        if lowest_port not in reserved_ports:
            try:
                with contextlib.closing(socket.socket(*socket_args, **socket_kwargs)) as my_socket:
                    my_socket.bind((bind_address, lowest_port))
                    this_port = my_socket.getsockname()[1]
                    reserved_ports.add(this_port)
                    return this_port
            except socket.error as error:
                if not error.errno == errno.EADDRINUSE:
                    raise
                assert not lowest_port == 0
                reserved_ports.add(lowest_port)
        lowest_port += 1
    raise Exception('Could not find open port')