在使用mediapipe库之前需要先导入cv2库，否则会提示“name 'cv2' is not defined”的错误。 示例代码：

import cv2
import mediapipe as mp

cap = cv2.VideoCapture(0)
with mp.solutions.hands.Hands() as hands:
    while True:
        success, image = cap.read()
        if not success:
            print("Ignoring empty camera frame.")
            continue
        image = cv2.cvtColor(cv2.flip(image, 1), cv2.COLOR_BGR2RGB)
        image.flags.writeable = False
        results = hands.process(image)
        image.flags.writeable = True
        image = cv2.cvtColor(image, cv2.COLOR_RGB2BGR)
        cv2.imshow('MediaPipe Hands', image)
        if cv2.waitKey(5) & 0xFF == 27:
            break
cap.release()
cv2.destroyAllWindows()

在以上代码中，先导入了cv2库，再进行mediapipe库的使用，可以避免“cv2 not work after install mediapipe library”的问题。