Calculates and returns a dictionary of filenames and CRC32

        :returns: dict of filename: CRC32

def get_files_crc32(self):
        """
        Calculates and returns a dictionary of filenames and CRC32

        :returns: dict of filename: CRC32
        """
        if self.files_crc32 == {}:
            for i in self.get_files():
                self._get_crc32(i)

        return self.files_crc32