opencv 2 or 3 debugging? [closed]

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I'm very interested in this code below taken from[this page] (http://opencvpython.blogspot.in/2012/...)

I try and run it but get the error:

cv2.accumulateWeighted(f,avg1,0.1)
TypeError: dst is not a numpy array, neither a scalar

1) I'm running opencv2 but is this code only for open cv3?

I go to this page to find out if individual lines are opencv 2 or 3, but it doesn't tell me.

2) If this code is for opencv3 is there something similar for opencv 2 or a good examples page for opencv2?

3) Is there any documentation that would enable me to check if individual lines of code are 2 or 3, because I don't want to debug code that will never work on my system, because I have the wrong version of opencv installed.

4) can I have opencv2 and 3 installed on my machine, or if I have opencv3 do I need opencv2 at all?

import cv2
import numpy as np

c = cv2.VideoCapture(0)



_,f = c.read()

avg1 = np.float32(f)
avg2 = np.float32(f)


while(1):
    _,f = c.read()

    cv2.accumulateWeighted(f,avg1,0.1)
    cv2.accumulateWeighted(f,avg2,0.01)

    res1 = cv2.convertScaleAbs(avg1)
    res2 = cv2.convertScaleAbs(avg2)

    cv2.imshow('img',f)
    cv2.imshow('avg1',res1)
    cv2.imshow('avg2',res2)
    k = cv2.waitKey(20)

    if k == 27:
        break