(self, tz)
Set timezone value:
        - if self._timezone is None set it to new timezone
        - if current timezone is different that new indicate that TimeVariable
          have two date-times with different timezones
        - if timezones are same keep it
Set timezone value:
        - if self._timezone is None set it to new timezone
        - if current timezone is different that new indicate that TimeVariable
          have two date-times with different timezones
        - if timezones are same keep it
Set timezone value : - if self . _timezone is None set it to new timezone - if current timezone is different that new indicate that TimeVariable have two date - times with different timezones - if timezones are same keep it
def timezone(self, tz):
        """
        Set timezone value:
        - if self._timezone is None set it to new timezone
        - if current timezone is different that new indicate that TimeVariable
          have two date-times with different timezones
        - if timezones are same keep it
        """
        if self._timezone is None:
            self._timezone = tz
        elif tz != self.timezone:
            self._timezone = "different timezones"
def timezone ( self , tz ) : if self . _timezone is None : self . _timezone = tz elif tz != self . timezone : self . _timezone = "different timezones"