def _is_epub(file_bytes: bytes) -> bool:
	"""
	Decide if a file is an epub file.
	From https://github.com/h2non/filetype.py (MIT license)
	"""

	return (len(file_bytes) > 57 and
		file_bytes[0] == 0x50 and file_bytes[1] == 0x4B and
		file_bytes[2] == 0x3 and file_bytes[3] == 0x4 and
		file_bytes[30] == 0x6D and file_bytes[31] == 0x69 and
		file_bytes[32] == 0x6D and file_bytes[33] == 0x65 and
		file_bytes[34] == 0x74 and file_bytes[35] == 0x79 and
		file_bytes[36] == 0x70 and file_bytes[37] == 0x65 and
		file_bytes[38] == 0x61 and file_bytes[39] == 0x70 and
		file_bytes[40] == 0x70 and file_bytes[41] == 0x6C and
		file_bytes[42] == 0x69 and file_bytes[43] == 0x63 and
		file_bytes[44] == 0x61 and file_bytes[45] == 0x74 and
		file_bytes[46] == 0x69 and file_bytes[47] == 0x6F and
		file_bytes[48] == 0x6E and file_bytes[49] == 0x2F and
		file_bytes[50] == 0x65 and file_bytes[51] == 0x70 and
		file_bytes[52] == 0x75 and file_bytes[53] == 0x62 and
		file_bytes[54] == 0x2B and file_bytes[55] == 0x7A and
		file_bytes[56] == 0x69 and file_bytes[57] == 0x70)