When you say [:-1] you are stripping the last element. Instead of slicing the string, you can apply startswith and endswith on the string object itself like this
if str1.startswith('"') and str1.endswith('"'):
So the whole program becomes like this
>>> str1 = '"xxx"'
>>> if str1.startswith('"') and str1.endswith('"'):
... print "hi"
>>> else:
... print "condition fails"
...
hi
Even simpler, with a conditional expression, like this
>>> print("hi" if str1.startswith('"') and str1.endswith('"') else "fails")
hi