set_proxy(proxy_type, addr[, port[, rdns[, username[, password]]]])
        Sets the proxy to be used.

        proxy_type -    The type of the proxy to be used. Three types
                        are supported: PROXY_TYPE_SOCKS4 (including socks4a),
                        PROXY_TYPE_SOCKS5 and PROXY_TYPE_HTTP
        addr -        The address of the server (IP or DNS).
        port -        The port of the server. Defaults to 1080 for SOCKS
                       servers and 8080 for HTTP proxy servers.
        rdns -        Should DNS queries be performed on the remote side
                       (rather than the local side). The default is True.
                       Note: This has no effect with SOCKS4 servers.
        username -    Username to authenticate with to the server.
                       The default is no authentication.
        password -    Password to authenticate with to the server.
                       Only relevant when username is also provided.

def set_proxy(self, proxy_type=None, addr=None, port=None, rdns=True, username=None, password=None):
        """set_proxy(proxy_type, addr[, port[, rdns[, username[, password]]]])
        Sets the proxy to be used.

        proxy_type -    The type of the proxy to be used. Three types
                        are supported: PROXY_TYPE_SOCKS4 (including socks4a),
                        PROXY_TYPE_SOCKS5 and PROXY_TYPE_HTTP
        addr -        The address of the server (IP or DNS).
        port -        The port of the server. Defaults to 1080 for SOCKS
                       servers and 8080 for HTTP proxy servers.
        rdns -        Should DNS queries be performed on the remote side
                       (rather than the local side). The default is True.
                       Note: This has no effect with SOCKS4 servers.
        username -    Username to authenticate with to the server.
                       The default is no authentication.
        password -    Password to authenticate with to the server.
                       Only relevant when username is also provided.
        """
        self.proxy = (proxy_type, addr, port, rdns,
                      username.encode() if username else None,
                      password.encode() if password else None)