So, assume we have an array like that: 4,6,9,10,2,25,12,6,9
And then I try to calculate quantiles with numpy.quantile and statistics.quantile

```
import numpy as np
from statistics import quantiles
arr = np.array([4,6,9,10,2,25,12,6,9,])
np.quantile(arr, (0.25, 0.50, 0.75))
quantiles(arr)

```

When I calculate with numpy the result: 
`array([ 6., 9., 10.])`

When I calculate with statistics the result: 
`[5.0, 9.0, 11.0]`

So which library is calculating correctly?