Function pascal_triangle

# Builds Pascal's triangle line ## Definition We can obtain any given line of the [pascal triangle](https://en.wikipedia.org/wiki/Pascal%27s_triangle) by using the formula defined here: $$ e_n^k = \binom{n}{k} $$ Where $e_n^k$ is the element of the $n^{th}$ line and $i^{th}$ position. The first position of the triangle is number as line 0, the rest follows from there. ## Inputs - `n`: the index

(n: usize)