def ping(proxy=None, hostport=None):
    """
    rpc_ping
    Returns {'alive': True} on succcess
    Returns {'error': ...} on error
    """
    schema = {
        'type': 'object',
        'properties': {
            'status': {
                'type': 'string'
            },
        },
        'required': [
            'status'
        ]
    }

    assert proxy or hostport, 'Need either proxy handle or hostport string'
    if proxy is None:
        proxy = connect_hostport(hostport)

    resp = {}

    try:
        resp = proxy.ping()
        resp = json_validate( schema, resp )
        if json_is_error(resp):
            return resp

        assert resp['status'] == 'alive'

    except ValidationError as e:
        if BLOCKSTACK_DEBUG:
            log.exception(e)

        resp = {'error': 'Server response did not match expected schema.  You are likely communicating with an out-of-date Blockstack node.', 'http_status': 502}
        return resp

    except socket.timeout:
        log.error("Connection timed out")
        resp = {'error': 'Connection to remote host timed out.', 'http_status': 503}
        return resp

    except socket.error as se:
        log.error("Connection error {}".format(se.errno))
        resp = {'error': 'Connection to remote host failed.', 'http_status': 502}
        return resp

    except Exception as ee:
        if BLOCKSTACK_DEBUG:
            log.exception(ee)

        log.error("Caught exception while connecting to Blockstack node: {}".format(ee))
        resp = {'error': 'Failed to contact Blockstack node.  Try again with `--debug`.', 'http_status': 500}
        return resp

    return resp
rpc_ping
    Returns {'alive': True} on succcess
    Returns {'error': ...} on error