<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def __isValidZIP(self, suffix):

 """Determine if the suffix is `.zip` format"""

        if suffix and isinstance(suffix, string_types):
            if suffix.endswith(".zip"):
                return True
        return False