Finding coordinates of face in Python[Updated]

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I am trying to send the coordinates of a face found with opencv over serial. I got the serial part downpath but I can't figure out how to find the coordinates of the face. I would like to if possible use the facedetection.py example as the base... Any ideas? Thanks ahead of time! Here is the facedetect.py code:

#!/usr/bin/env python

import numpy as np
import cv2

# local modules
from video import create_capture
from common import clock, draw_str

help_message = '''
USAGE: facedetect.py [--cascade <cascade_fn>] [--nested-cascade <cascade_fn>] [<video_source>]
'''

def detect(img, cascade):
    rects = cascade.detectMultiScale(img, scaleFactor=1.3, minNeighbors=4, minSize=(30, 30), flags = cv2.CASCADE_SCALE_IMAGE)
    if len(rects) == 0:
        return []
    rects[:,2:] += rects[:,:2]
    return rects

def draw_rects(img, rects, color):
    for x1, y1, x2, y2 in rects:
        cv2.rectangle(img, (x1, y1), (x2, y2), color, 2)

if __name__ == '__main__':
    import sys, getopt
    print help_message

    args, video_src = getopt.getopt(sys.argv[1:], '', ['cascade=', 'nested-cascade='])
    try:
        video_src = video_src[0]
    except:
        video_src = 0
    args = dict(args)
    cascade_fn = args.get('--cascade', "../../data/haarcascades/haarcascade_frontalface_alt.xml")
    nested_fn  = args.get('--nested-cascade', "../../data/haarcascades/haarcascade_eye.xml")

    cascade = cv2.CascadeClassifier(cascade_fn)
    nested = cv2.CascadeClassifier(nested_fn)

    cam = create_capture(video_src, fallback='synth:bg=../cpp/lena.jpg:noise=0.05')

    while True:
        ret, img = cam.read()
        gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
        gray = cv2.equalizeHist(gray)

        t = clock()
        rects = detect(gray, cascade)
        vis = img.copy()
        draw_rects(vis, rects, (0, 255, 0))
        for x1, y1, x2, y2 in rects:
            roi = gray[y1:y2, x1:x2]
            vis_roi = vis[y1:y2, x1:x2]
            subrects = detect(roi.copy(), nested)
            draw_rects(vis_roi, subrects, (255, 0, 0))
        dt = clock() - t

        draw_str(vis, (20, 20), 'time: %.1f ms' % (dt*1000))
        cv2.imshow('facedetect', vis)

        if 0xFF & cv2.waitKey(5) == 27:
            break
    cv2.destroyAllWindows()

Sorry about the formatting... Thanks for all the help so far!