Gap up gap down strategy does not work with security list

Blueshift
1

Course Name: Day Trading Strategies for Beginners, Section No: 9, Unit No: 1, Unit type: Document

Why is it not possible to run the strategy on Blueshift with a list of securities, also not with only one symbol in the list?
context.security = [symbol('AAPL'), symbol['AMZN')].
Errormessage: 
File "gap_up_down_strategy.py", line 72, in square_off
AttributeError: 'list' object has no attribute 'fx_rate'

2

ok, I solved it by my self. The logic in the functions has to be changed too