When I query metrics from prometheus, I just get the timestamp when I queried. 

For example, If I query data like this, 

`http://localhost:9090/api/v1/query?query=go_memstats_buck_hash_sys_bytes`

Then I got the response like following. 

```
{
    "status": "success",
    "data": {
        "resultType": "vector",
        "result": [
            {
                "metric": {
                    "__name__": "go_memstats_buck_hash_sys_bytes",
                    "instance": "localhost:9090",
                    "job": "prometheus"
                },
                "value": [
                    1557366670.588, <== UNIX time stamp when I queried.
                    "1472884" <== Value
                ]
            }
        ]
    }
}

```

But in the graph view, I can see the graph like following. It means I can query data with timestamp that prometheus. 

[![enter image description here](https://i.stack.imgur.com/t5ppC.png)](https://i.stack.imgur.com/t5ppC.png)

I wanna know how to query metrics with timestamp that prometheus has.