code: def get_user(uid):
      
      try:
          acl_url = urljoin(_acl_url(), 'users/{}'.format(uid))
          r = http.get(acl_url)
          return r.json()
          # assert r.status_code == 201
      except DCOSHTTPException as e:
          if e.response.status_code == 400:
              return None
          else:
              raise
docs: Returns a user from the DCOS Enterprise.  It returns None if none exists.
  
          :param uid: user id
          :type uid: str
          :return: User
          :rtype: dict