vs code python保存時pylint提示"Unable to import 'flask'"

在配置vscode python開發環境時，編寫如下代碼並保存時，會提示Unable to import 'flask'

from flask import Flask

app = Flask(__name__)

tasks = [
    {
        'id': 1,
        'title': u'Buy groceries',
        'description': u'Milk, Cheese, Pizza, Fruit, Tylenol', 
        'done': False
    },
    {
        'id': 2,
        'title': u'Learn Python',
        'description': u'Need to find a good Python tutorial on the web', 
        'done': False
    }
]

已安裝pylint

pip install pylint

這個時候需要配置vscode,對應鏈接https://code.visualstudio.com/docs/python/environments