Kakuro solver in Python

kakuro.py

import itertools
from copy import deepcopy

def possible_combinations(values, n, total):
	# generate all combinations of given values with given sum
	return [combination for combination in itertools.combinations(values, n) if sum(combination) == total]

def make_aval(board, clues):
	"""
	Generates a set of all digits you can use in each cell, just like you do in sudoku board
	"""
	for total, coords in clues:
		# a set of all the digits you can use, excluding the ones already used
		all_aval = set(range(1, 10)) - set(board[coord]["val"] for coord in coords)
		# a number of all cells you still have to fill
		n_empty = len([1 for coord in coords if board[coord]["val"] == 0])
		# a sum you have to get, minus the numbers already written
		total -= sum(board[coord]["val"] for coord in coords)
		# all combinations of digits you can enter
		combinations = possible_combinations(all_aval, n_empty, total)
		# a set of all the digits you can enter in these cells based on this clue
		all_aval = {num for combination in combinations for num in combination}
		# only these digits can be used in these cells, so let's intersect the available digit sets
		for coord in coords:
			board[coord]["aval"] &= all_aval

def load_data():
	first_board = {}
	clues = []
	_, *lines = open("inputs.txt").read().splitlines()
	for line in lines:
		total, *coords = line.split()
		for coord in coords:
			first_board[coord] = {"val": 0, "aval": set(range(1, 10))}
		clues.append((int(total), coords))
	return first_board, clues


def print_board(board):
	for key in sorted(board):
		print(key, board[key])
	print("")

def main():
	boards = []
	solutions = []

	first_board, clues = load_data()
	boards.append(first_board)	

	# while there are still not-finished boards to analyze:
	while boards:
		# take the last one
		board = boards.pop()

		# generate all the available digits
		make_aval(board, clues)
		# if there is any empty cell with no available digits, the board is invalid
		if any(cell["val"] == 0 and len(cell["aval"]) == 0 for cell in board.values()):
			continue
		# if all cells are filled, we've found a solution
		if all(cell["val"] != 0 for cell in board.values()):
			solutions.append(board)
			continue

		# find the first empty cell you can try filling		
		coord = next(coord for coord in sorted(board) if board[coord]["val"] == 0)
		# for each digit you can use in this cell:
		for candidate in board[coord]["aval"]:
			new_board = deepcopy(board)
			# insert this digit in this cell
			new_board[coord]["val"] = candidate
			boards.append(new_board)

	for solution in solutions:
		print_board(solution)

if __name__ == "__main__":
	main()

Please, can you give a sample input format and a sample output format.
Also can this code check if multiple possible solutions exists