def set_proxy(self, host, port, user=None, password=None):
self._httpclient.set_proxy(host, port, user, password)<EOL>
Sets the proxy server host and port for the HTTP CONNECT Tunnelling.

:param str host: Address of the proxy. Ex: '192.168.0.100'
:param int port: Port of the proxy. Ex: 6000
:param str user: User for proxy authorization.
:param str password: Password for proxy authorization.