Saving multiple videos at the same time with opencv - opencv

Question

For my project I have multiple cameras and I need to save the video feed to multiple output files at the same time. Here's my code:
import cv2
def one_cam_is_open(list_of_cams):
for cam in list_of_cams:
if cam.isOpened():
return True
return False
cam_list = []
# Capture video from camera
for i in range(0, 2):
cap = cv2.VideoCapture(i)
if cap!=-1:
cam_list.append(cv2.VideoCapture(i))
# the width and height of all cameras will be 1900x1080
width = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH) + 0.5)
height = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT) + 0.5)
dim = (1900, 1080)
# Define the codec and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc(*'mp4v') # Be sure to use the lower case
video_writers = {}
for i, cam in enumerate(cam_list):
video_writers[cam] = cv2.VideoWriter("output_" + str(i) + ".mp4", fourcc, 20.0, dim)
while one_cam_is_open(cam_list):
for (cam, out) in video_writers:#TypeError: cannot unpack non-iterable cv2.VideoCapture object
ret, frame = cam.read()
if ret == True:
frame = cv2.flip(frame, 0)
# write the flipped frame
out.write(frame)
cv2.imshow('frame', frame)
if (cv2.waitKey(1) & 0xFF) == ord('q'): # Hit `q` to exit
break
else:
break
# Release everything if job is finished
for (cam, out) in video_writers:
out.release()
cam.release()
cv2.destroyAllWindows()
As noted in the code, I get the error TypeError: cannot unpack non-iterable cv2.VideoCapture object when I try to unpack the references to the VideoWriter obejects for each camera.
Is there a way to write to multiple video files using VideoWriter?