Tic-tac-toe board

"""
board.py

Store a 3 by 3 tic-tac-toe board in a list of 3 lists.
"""

import sys

b = [
    ["X", " ", " "],
    [" ", "O", "O"],
    [" ", " ", "X"]
]

print("".join(b[0]))   #b[0] is a list of 3 strings.
print("".join(b[1]))
print("".join(b[2]))
print()

#Print a string of 5 lines, containing 9 pockets.

print(f"""\
{b[0][0]} | {b[0][1]} | {b[0][2]}
--+---+--
{b[1][0]} | {b[1][1]} | {b[1][2]}
--+---+--
{b[2][0]} | {b[2][1]} | {b[2][2]}
""", end = "")

sys.exit(0)

X  
 OO
  X

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

Things to try

1. Another way to store the board is in a 9-character string.

   b = "X   OO  X"
   

   b = "X...OO..X"       #easier to understand
   

   b = "X.." ".OO" "..X" #The 3 consecutive string literals are concatenated.
   

   I broke the string into three literals so we could write them on top of each other:

   #Explicit line joining.
   
   b = \
       "X.." \
       ".OO" \
       "..X"
   

   #Implicit line joining.
   
   b = (
       "X.."   #row 0
       ".OO"   #row 1
       "..X"   #row 2
   )
   

2. See if the board contains a winning position.

   #b is a string of 9 characters.
   
   b = (
       "XX."   #row 0
       "XOO"   #row 1
       "X.O"   #row 2
   )
   
   lines = [   #lines is a list of 8 strings.
       #3 rows
       b[:3],   #top row
       b[3:6],  #middle row
       b[6:],   #bottom row
   
       #3 columns
       b[::3],  #left column
       b[1::3], #middle column
       b[2::3], #right column
   
       #2 diagonals
       b[::4],  #upper left to lower right
       b[2:8:2] #upper right to lower left
   ]
   
   for c in ["X", "O"]:
       if 3 * c in lines:
           print(f"{c} won.")
   

   X won.
   

   Change the for loop to

   winners = [c for c in "XO" if 3 * c in lines]   #winners is a list of at most 2 strings.
   print("The winner(s):", *winners)
   

   The winner(s): X
   

3. The only reason we create the list args is to unpack it in the next very next statement. 8 * verse[1] (without the outer [square brackets]) would have been one very long string, not a list of 8 strings.

   """
   Output the lyrics to "Old MacDonald Had a Farm".
   """
   
   import sys
   
   verses = [
       ["cow",  "moo"],
       ["duck", "quack"],
       ["pig",  "oink"],
       ["dog",  "woof"]   #etc.
   ]
   
   line = "Old MacDonald had a farm, E-I-E-I-O!"
   
   paragraph = """\
   And on that farm he had a {}, E-I-E-I-O!
   With a {}-{} here and a {}-{} there,
   Here a {}, there a {},
   Everywhere a {}-{},
   """
   
   print(line)
   
   for verse in verses:
       args = 8 * [verse[1]]   #args is a list of 8 strings.
       print(paragraph.format(verse[0], *args), end = "")
       print(line)
       print()
   
   sys.exit(0)
   

   Old MacDonald had a farm, E-I-E-I-O!
   And on that farm he had a cow, E-I-E-I-O!
   With a moo-moo here and a moo-moo there,
   Here a moo, there a moo,
   Everywhere a moo-moo,
   Old MacDonald had a farm, E-I-E-I-O!
   
   And on that farm he had a duck, E-I-E-I-O!
   With a quack-quack here and a quack-quack there,
   Here a quack, there a quack,
   Everywhere a quack-quack,
   Old MacDonald had a farm, E-I-E-I-O!
   
   And on that farm he had a pig, E-I-E-I-O!
   With a oink-oink here and a oink-oink there,
   Here a oink, there a oink,
   Everywhere a oink-oink,
   Old MacDonald had a farm, E-I-E-I-O!
   
   And on that farm he had a dog, E-I-E-I-O!
   With a woof-woof here and a woof-woof there,
   Here a woof, there a woof,
   Everywhere a woof-woof,
   Old MacDonald had a farm, E-I-E-I-O!
   
   

4. """
   Output the lyrics to "If I Had a Hammer".
   """
   
   import sys
   
   #The first three verses.
   
   verses = [
       ["hammer", "hammer",  "hammer", "Well", "hammer",       "of justice"],
       ["bell",   "ring it", "ring",   "And",  "bell",         "of freedom"],
       ["song",   "sing it", "sing",   "And",  "song to sing", "about love between my brothers and my sisters"]
   ]
   
   all = "All over this land."
   
   for verse in verses:
       print(f"If I had a {verse[0]}")
       print(f"I'd {verse[1]} in the morning")
       print(f"I'd {verse[1]} in the evening")
       print(all)
   
       for object in ["danger", "warning", "love between my brothers and my sisters"]:
           print(f"I'd {verse[2]} out {object}")
   
       print(all)
       print()
   
   #The fourth verse.
   
   for verse in verses:
       print(f"{verse[3]} I got a {verse[4]}")
   print(all)
   
   for _ in range(2):
       for verse in verses:
           print(f"It's the {verse[0]} {verse[5]}")
       print(all)
   
   sys.exit(0)
   

   If I had a hammer
   I'd hammer in the morning
   I'd hammer in the evening
   All over this land.
   I'd hammer out danger
   I'd hammer out warning
   I'd hammer out love between my brothers and my sisters
   All over this land.
   
   If I had a bell
   I'd ring it in the morning
   I'd ring it in the evening
   All over this land.
   I'd ring out danger
   I'd ring out warning
   I'd ring out love between my brothers and my sisters
   All over this land.
   
   If I had a song
   I'd sing it in the morning
   I'd sing it in the evening
   All over this land.
   I'd sing out danger
   I'd sing out warning
   I'd sing out love between my brothers and my sisters
   All over this land.
   
   Well I got a hammer
   And I got a bell
   And I got a song to sing
   All over this land.
   It's the hammer of justice
   It's the bell of freedom
   It's the song about love between my brothers and my sisters
   All over this land.
   It's the hammer of justice
   It's the bell of freedom
   It's the song about love between my brothers and my sisters
   All over this land.