code: def revoke(self, cidr_ip=None, ec2_group=None):
          
          if isinstance(ec2_group, SecurityGroup):
              group_name = ec2_group.name
              group_owner_id = ec2_group.owner_id
              return self.connection.revoke_dbsecurity_group(
                  self.name,
                  ec2_security_group_name=group_name,
                  ec2_security_group_owner_id=group_owner_id)
  
          # Revoking by CIDR IP range
          return self.connection.revoke_dbsecurity_group(
              self.name, cidr_ip=cidr_ip)
docs: Revoke access to a CIDR range or EC2 SecurityGroup.
          You need to pass in either a CIDR block or
          an EC2 SecurityGroup from which to revoke access.
  
          @type cidr_ip: string
          @param cidr_ip: A valid CIDR IP range to revoke
  
          @type ec2_group: :class:`boto.ec2.securitygroup.SecurityGroup>`
  
          @rtype: bool
          @return: True if successful.