不理解这段函数式编程，看不懂

Question

const TOKEN = '123'const ROOT = '//www.baidu.com'const root = createAPI => (...args) => {  const result = createAPI(...args)  return {...result, url: `${ROOT}${result.url}`}}const auth = createAPI => (...args) => {  const result = createAPI(...args)  return {    ...result,    headers: {...result.headers, authorization: `Bearer ${TOKEN}`},  }}const projects = team => {  return {    url: `/api/0/teams/${team}/projects/`,  }}root(auth(projects))('fe')// 返回值如下{   headers: {authorization: "Bearer 123"}   url: "//www.baidu.com/api/0/teams/fe/projects/"}不理解这段函数式编程，看不懂,谁能详细解释下？### 你期待的结果是什么？实际看到的错误信息又是什么？