Programming the Playfair cipher in case anyone has heard about it. 

I ask the user to input a keyword (Example: bookkeeping), I then remove repeated letters (Example: bokeping). I need to create a 5x5 matrix and fill it with chars but declaring

```
    matrix = [][]

```

is marked as "Invalid syntax". I then need to fill up the matrix with the unique characters and then the rest of the letters of the alphabet (after removing the unique keyword characters) to end up with (i and j are placed on the same position):

```
    [b, o, k, e, p]
    [ij, n, g, a, c]
    [d, f, h, l, m]
    [q, r, s, t, u]
    [v, w, x, y, z]

```

Question 1: How do I properly declare the matrix to use it for this?

Question 2: How do I fill up the matrix with the keyword and then the rest of the characters?

Other than that, any suggestions?

Thank you for your help.