code: def param_apropos(self, args):
          '''search parameter help for a keyword, list those parameters'''
          if len(args) == 0:
              print("Usage: param apropos keyword")
              return
  
          htree = self.param_help_tree()
          if htree is None:
              return
  
          contains = {}
          for keyword in args:
              for param in htree.keys():
                  if str(htree[param]).find(keyword) != -1:
                      contains[param] = True
          for param in contains.keys():
              print("%s" % (param,)f param_apropos(self, args):
          '''search parameter help for a keyword, list those parameters'''
          if len(args) == 0:
              print("Usage: param apropos keyword")
              return
  
          htree = self.param_help_tree()
          if htree is None:
              return
  
          contains = {}
          for keyword in args:
              for param in htree.keys():
                  if str(htree[param]).find(keyword) != -1:
                      contains[param] = True
          for param in contains.keys():
              print("%s" % (param,))
docs: search parameter help for a keyword, list those parameters