code: def get_user(self, user_id=None, username=None, email=None):
          
          if user_id:
              uri = "/users/%s" % user_id
          elif username:
              uri = "/users?name=%s" % username
          elif email:
              uri = "/users?email=%s" % email
          else:
              raise ValueError("You must include one of 'user_id', "
                      "'username', or 'email' when calling get_user().")
          resp, resp_body = self.method_get(uri)
          if resp.status_code == 404:
              raise exc.NotFound("No such user exists.")
          users = resp_body.get("users", [])
          if users:
              return [User(self, user) for user in users]
          else:
              user = resp_body.get("user", {})
              if user:
                  return User(self, user)
              else:
                  raise exc.NotFound("No such user exists.")
docs: Returns the user specified by either ID, username or email.
  
          Since more than user can have the same email address, searching by that
          term will return a list of 1 or more User objects. Searching by
          username or ID will return a single User.
  
          If a user_id that doesn't belong to the current account is searched
          for, a Forbidden exception is raised. When searching by username or
          email, a NotFound exception is raised if there is no matching user.