Python complains that class instance is not defined

[colt]

Hello. I have this code line:

instruction = Instruction (byte)

that generates the following error message:

Traceback (most recent call last):
File "emulator.py", line 29, in <module>
main ()
File "emulator.py", line 21, in main
instruction = Instruction (byte)
NameError: global name 'Instruction' is not defined

Instruction code it is:

class Instruction (object):
	def __init___(self, identifier_byte):
		#type: (byte) ->
		self.identifier_byte = identifier_byte

So, what I am fogetting? Thanks for the input.