code: def serialize_assign(self, op):
          
          elem = etree.Element('assign')
          self.serialize_value(SubElement(elem, 'name'), op.left_attribute)
          if op.right:
              self.serialize_value(SubElement(elem, 'value'), op.right)
          if op.right_attribute:
              self.serialize_value(
                  SubElement(elem, 'value-attribute'), op.right_attribute)
          return elem
docs: Serializer for :meth:`SpiffWorkflow.operators.Assign`.
  
          Example::
  
              <assign>
                  <name>foobar</name>
                  <value>doodle</value>
              </assign>