impossible to match a string pattern with a quotation mark in an opened file 
[code]
file = '''it's an opened file made of "strings"'''
if '''"string"''' in file:
____print('ok')
else:
____print('none')
[/code]
in iddle, it works with no difficulties...
but if the file comes from an file = open(fileadress).read()

the same code return nothing... it do not find the pattern string, and just because of double quote marks (i've not tried with some other marks)

for me it's a bug, because it do works well, if their no quotation marks