NameError: name 'buy_signal' is not defined

[kam dorra]

NameError: name 'buy_signal' is not defined

Get this error: NameError: name 'buy_signal' is not defined
even though I have defined 'buy_signal' in def __init__(self):

	def __init__(self):
		buy_signal = bt.If(A < float('Inf'), c(0) > B, False)
		sell_signal = bt.If(C < float('Inf'), c(0) < D, False)

	def next(self):
		if buy_signal[0]:
			self.buy()
		elif sell_signal[0] and self.position > 0:
			self.close()

Thanks.

[backtrader]

https://pythontips.com/2013/08/07/the-self-variable-in-python-explained/