Code the functions

How do we draw the board?

for example:

X | X | X
--+---+--
O | O | X
--+---+--
O | X | O

You can see:

• value of each cell, separated by pipe symbol
• separating horizontal line

What our code should do:

• prepare text for every data line
• prepare text for separator line
• display prepared text on the screen

Now, in the first lines we should have:

def draw_board(cells):
  # prepare output data
  line_separator = "--+--+--"
  line_1 = cells[0] + " | " + cells[1] + " | " + cells[2]
  line_2 = cells[3] + " | " + cells[4] + " | " + cells[5]
  line_3 = cells[6] + " | " + cells[7] + " | " + cells[8]
  # print output data
  print(line_1)
  print(line_separator)
  print(line_2)
  print(line_separator)
  print(line_3)

and so on

So you basically repeat the steps of breaking down the tasks until you know how to do them. That's the magic behind writing code :)