docs: def toxml(self):
          """
          Exports this object into a LEMS XML object
          """
  
          return '<DerivedParameter name="{0}"'.format(self.name) +\
            (' dimension="{0}"'.format(self.dimension) if self.dimension else '') +\
            (' value="{0}"'.format(self.value) if self.value else '') +\
            '/>'