Issue running example 3a

[sjm5467]

I ran your example 3a and was fine until I ran the tracking code and got the error below.

I had some issues with the install, so maybe I'm missing something there.
Thanks,
~Sara

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AttributeError Traceback (most recent call last)
in ()
25 frame = cv2.resize(frame, None, fx = scaling, fy = scaling, interpolation = cv2.INTER_LINEAR)
26 thresh = tr.colour_to_thresh(frame, block_size, offset)
---> 27 final, contours, meas_last, meas_now = tr.detect_and_draw_contours(frame, thresh, meas_last, meas_now, min_area, max_area)
28 row_ind, col_ind = tr.hungarian_algorithm(meas_last, meas_now)
29 final, meas_now, df = tr.reorder_and_draw(final, colours, n_inds, col_ind, meas_now, df, mot, this)

/Users/Sara/tracktor-master/examples/tracktor.py in detect_and_draw_contours(frame, thresh, meas_last, meas_now, min_area, max_area)
74
75 i = 0
---> 76 meas_last = meas_now.copy()
77 del meas_now[:]
78 while i < len(contours):

AttributeError: 'list' object has no attribute 'copy'