**Input:** None.

**Goal:** Return the inverse of the following matrix:

$$\begin{bmatrix} 1 & 2 \\ 3 & 4 \end{bmatrix}$$

<details>
  <summary><b>Need a hint?</b></summary>
  
You may find [this Wikipedia article](https://en.wikipedia.org/wiki/Invertible_matrix#Inversion_of_2_%C3%97_2_matrices) useful.

</details>
