import chess.pgn

def print_all_prefixes(game):
    # Create an exporter that prints the PGN header and moves (but not comments/variations).
    exporter = chess.pgn.StringExporter(headers=True, variations=False, comments=False)
    node = game
    while True:
        # Print the PGN for the game prefix ending at the current node.
        print(node.accept(exporter))
        if node.is_end():
            break
        # Move to the next move in the mainline.
        node = node.variation(0)

import chess.pgn

def print_all_prefixes(game):
    # Create an exporter that prints the PGN header and moves (but not comments/variations).
    exporter = chess.pgn.StringExporter(headers=True, variations=False, comments=False)
    node = game
    while True:
        # Print the PGN for the game prefix ending at the current node.
        print(node.accept(exporter))
        if node.is_end():
            break
        # Move to the next move in the mainline.
        node = node.variation(0)


import io
import chess.pgn
print_all_prefixes(chess.pgn.read_game(io.StringIO('1. Nf3 Nf6 2. c4 g6 3. Nc3 Bg7 4. d4 O-O 5. Bf4 d5 6. Qb3 dxc4 7. Qxc4 c6 8. e4 Nbd7 9. Rd1 Nb6 10. Qc5 Bg4 11. Bg5 Na4 12. Qa3 Nxc3 13. bxc3 Nxe4 14. Bxe7 Qb6 15. Bc4 Nxc3')))

import chess.pgn

def print_all_prefixes(game):
    # Get the list of mainline moves from the game.
    moves = list(game.mainline_moves())
    
    # For each prefix, rebuild the game and print its PGN.
    for i in range(len(moves)):
        # Create a new game and copy the headers.
        prefix_game = chess.pgn.Game()
        prefix_game.headers = game.headers.copy()
        node = prefix_game
        
        # Add the moves for this prefix.
        for move in moves[:i+1]:
            node = node.add_main_variation(move)
        
        # Print the PGN notation for this prefix.
        print(prefix_game)

import chess.pgn

def print_all_prefixes(game):
    # Get the list of mainline moves from the game.
    moves = list(game.mainline_moves())
    
    # For each prefix, rebuild the game and print its PGN.
    for i in range(len(moves)):
        # Create a new game and copy the headers.
        prefix_game = chess.pgn.Game()
        prefix_game.headers = game.headers.copy()
        node = prefix_game
        
        # Add the moves for this prefix.
        for move in moves[:i+1]:
            node = node.add_main_variation(move)
        
        # Print the PGN notation for this prefix.
        print(prefix_game)


import io
import chess.pgn
print_all_prefixes(chess.pgn.read_game(io.StringIO('1. Nf3 Nf6 2. c4 g6 3. Nc3 Bg7 4. d4 O-O 5. Bf4 d5 6. Qb3 dxc4 7. Qxc4 c6 8. e4 Nbd7 9. Rd1 Nb6 10. Qc5 Bg4 11. Bg5 Na4 12. Qa3 Nxc3 13. bxc3 Nxe4 14. Bxe7 Qb6 15. Bc4 Nxc3')))