18.py

import difflib


def main():
 left, right = first_step()
 diff = second_step(left, right)
 third_step(diff)


def first_step():
 deltas = open("swan/deltas", 'r')
 left = ""
 right = ""
 while True:
 line = deltas.readline()
 if line:
 left += line[:53]
 left += "\n"
 right += line[56:]
 else:
 break
 return left, right


def second_step(left, right):
 diff = difflib.ndiff(left.splitlines(keepends=True), right.splitlines(keepends=True))
 result = "".join(diff)
 return result


def third_step(diff):
 plus = open("swan/plus.png", "wb")
 subtraction = open("swan/subtraction.png", "wb")
 space = open("swan/space.png", "wb")
 lines = diff.split("\n")
 for line in lines:
 if len(line) > 0:
 first_byte = line[0]
 if first_byte == "+":
 write_file(plus, line)
 elif first_byte == "-":
 write_file(subtraction, line)
 elif first_byte == " ":
 write_file(space, line)


def write_file(file, strings):
 sub_strings = strings[2:]
 ary = sub_strings.split(" ")
 for point in ary:
 if point.isalnum():
 b = bytes.fromhex(point)
 file.write(b)


if __name__ == "__main__":
 main()