docs: def create_cssparameter(self, name=None, value=None):
          """
          Create a new L{CssParameter} node as a child of this element, and attach it to the DOM.
          Optionally set the name and value of the parameter, if they are both provided.
  
          @type   name: string
          @param  name: Optional. The name of the L{CssParameter}
          @type  value: string
          @param value: Optional. The value of the L{CssParameter}
          @rtype: L{CssParameter}
          @return: A new style parameter, set to the name and value.
          """
          elem = self._node.makeelement('{%s}CssParameter' % SLDNode._nsmap['sld'], nsmap=SLDNode._nsmap)
          self._node.append(elem)
  
          if not (name is None or value is None):
              elem.attrib['name'] = name
              elem.text = value
  
          return CssParameter(self, len(self._node) - 1)