# Trying to get the divided differences of a list of points

I was trying to get the divided differences of a list of points, then I had written

```
divided_difference((0,1), (1,4.5), (3,14.5), (5,28.5), (6,37))
```

but when I tried to execute it the notebook spit out

```

NameError Traceback (most recent call last) <ipython-input-1-7581bf64e41a> in <module>() ----> 1 divided_difference((Integer(0),Integer(1)), (Integer(1),RealNumber('4.5')), (Integer(3),RealNumber('14.5')), (Integer(5),RealNumber('28.5')), (Integer(6),Integer(37)))

NameError: name 'divided_difference' is not defined

```

However the function `divided_difference`

appear in the manual of SAGE related to polynomials. What Im doing wrong?