code: def find_deref_completions(ast_rootpath, root_env=gcl.default_env):
    
    with util.LogTime('find_deref_completions'):
      tup = inflate_context_tuple(ast_rootpath, root_env)
      path = path_until(ast_rootpath, is_deref_node)
      if not path:
        return {}
      deref = path[-1]
      haystack = deref.haystack(tup.env(tup))
      if not hasattr(haystack, 'keys'):
        return {}
      return {n: get_completion(haystack, n) for n in haystack.keys()}
docs: Returns a dict of { name => Completions }.