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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def fcs(bits):
	'''
	Append running bitwise FCS CRC checksum to end of generator
	'''
	fcs = FCS()
	for bit in bits:
		yield bit
		fcs.update_bit(bit)

#	test = bitarray()
#	for byte in (digest & 0xff, digest >> 8):
#		print byte
#		for i in range(8):
#			b = (byte >> i) & 1 == 1
#			test.append(b)
#			yield b

	# append fcs digest to bit stream

	# n.b. wire format is little-bit-endianness in addition to little-endian
	digest = bitarray(endian="little")
	digest.frombytes(fcs.digest())
	for bit in digest:
		yield bit