from datetime import datetime as dt, date
def englishBreakfast(x):
datediff = lambda d: abs(dt.strptime(date.today().strftime('%Y%m%d'), '%Y%m%d') - dt.strptime(d, '%Y%m%d')).days
result = []
for agent_code, start_date in x:
result += [[agent_code, datediff(start_date)]]
return result
x = [ [ '001', '20200109' ], [ '003', '20200101' ], [ '007', '20060712' ] ]
print(englishBreakfast(x))