# TypeError: Computation failed since Maxima requested additional constraints

I have the following code:

```
N, n, f = var('N, n, f')
assume(N>0)
sum(binomial(N, n)*f^n*(1-f)^(N-n), n, (N+1)/2, N)
```

It gives me the following error message:

```
TypeError: Computation failed since Maxima requested additional constraints (try the command 'assume(N+1>0)' before integral or limit evaluation, for example): Is N+1 positive, negative, or zero?
```