code: def search_definition(self, module, keyword, arg):
          
          r = module.search_one(keyword, arg)
          if r is not None:
              return r
          for i in module.search('include'):
              modulename = i.arg
              m = self.ctx.search_module(i.pos, modulename)
              if m is not None:
                  r = m.search_one(keyword, arg)
                  if r is not None:
                      return r
          return None
docs: Search for a defintion with `keyword` `name`
          Search the module and its submodules.