code: def get(self, instance, **kwargs):
          
          # The default value
          default = self.getDefault(instance)
  
          # Retrieve the proxy object
          proxy_object = self.get_proxy(instance)
  
          # Return None if we could not find a proxied object, e.g. through
          # the proxy expression 'context.getSample()' on an AR
          if proxy_object is None:
              logger.debug("Expression '{}' did not return a valid Proxy Object on {}"
                           .format(self.proxy, instance))
              return default
  
          # Lookup the proxied field by name
          field_name = self.getName()
          field = proxy_object.getField(field_name)
  
          # Bail out if the proxy object has no identical named field
          if field is None:
              raise KeyError("Object '{}' with id '{}' has no field named '{}'".format(
                  proxy_object.portal_type, proxy_object.getId(), field_name))
  
          # return the value of the proxy field
          return field.get(proxy_object)
docs: retrieves the value of the same named field on the proxy object