Exports this object into a LEMS XML object

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 '') +\
          '/>'