code: def is_safe(self):
          
          self.log(u"Checking if this container is safe")
          for entry in self.entries:
              if not self.is_entry_safe(entry):
                  self.log([u"This container is not safe: found unsafe entry '%s'", entry])
                  return False
          self.log(u"This container is safe")
          return True
docs: Return ``True`` if the container can be safely extracted,
          that is, if all its entries are safe, ``False`` otherwise.
  
          :rtype: bool
          :raises: same as :func:`~aeneas.container.Container.entries`