def delete(self, v):
        '''
        Removes the value `v` from the tree and returns the new (updated) tree.
        If `v` is a non-member, the same tree is returned without modification.
        '''

        if self.is_empty():
            return self
        if v < self.value():
            return self.cons(self.lc().delete(v),self.rc())
        if v > self.value():
            return self.cons(self.lc(),self.rc().delete(v))
        if v is self.value():
            return self.Unlink(v)
        else:
            return self


    def Unlink(self,v):
        if self.lc().value() is None and self.rc().value() is None:
            return self.set_value(None)

        if self.lc().value() is None:
            return self.rc()

        elif self.rc().value() is None:
            return self.lc()

        else:
            if self.rc().height() > self.lc().height():
                temp = self.rc().Minimum()
                self.set_value(temp)
                return self.cons(self.lc(),self.rc().delete(temp))
            else:
                temp = self.lc().Maximum()
                self.set_value(temp)
                return self.cons(self.lc().delete(temp),self.rc())


    def Minimum(self):
        if self.lc().value() is not None:
            return self.lc().value().Minimum()
        else:
            return self.value()

    def Maximum(self):
        if self.rc().value() is not None:
            return self.rc().value().Maximum()
        else:
            return self.value()