code: def remove_subsegment(self, subsegment):
          
          super(Subsegment, self).remove_subsegment(subsegment)
          self.parent_segment.decrement_subsegments_size()
docs: Remove input subsegment from child subsegemnts and
          decrement parent segment total subsegments count.
  
          :param Subsegment: subsegment to remove.