def store(key, message, in_path, out_path):
epub = Epub()
epub.expand(in_path)
space = Space(epub)
binary_message = ''.join([format(ord(x), '0'+str(CHAR_BIT_SIZE)+'b') for x in message])
message_size = format(len(binary_message), 'b')
header_size = format(len(message_size), '0'+str(HEADER_BIT_SIZE)+'b')
bits_to_write = header_size + message_size + binary_message
if (len(space)) < len(bits_to_write):
print 'Error, not enough space on the epub file'
line_order = LineOrder(key, len(space))
add_noise(space)
for bit in bits_to_write:
space[line_order.next()] = (bit == '1')
space.commit()
epub.contract(out_path)
