Adjust the _is_equals() method which would not work correctly if both color names were None. Python treats None == None as true, but that may not be correct here. 
Adjust the _is_equals() method which would not work correctly if both
color names were None. Python treats None == None as true, but that may
not be correct here. 
katerina7479/pypdflite,katerina7479/pypdflite,katerina7479/pypdflite