gunicorn -b '127.0.0.1:8000' bootstrap:app errror

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When I run 'gunicorn -b '127.0.0.1:8000' bootstrap:app' I got the error message as follows:
[2017-02-10 11:03:04 +0000] [7797] [INFO] Starting gunicorn 19.6.0
[2017-02-10 11:03:04 +0000] [7797] [INFO] Listening at: http://127.0.0.1:8000 (7797)
[2017-02-10 11:03:04 +0000] [7797] [INFO] Using worker: sync
[2017-02-10 11:03:04 +0000] [7802] [INFO] Booting worker with pid: 7802
[2017-02-10 11:03:04 +0000] [7802] [ERROR] Exception in worker process
Traceback (most recent call last):
File "/usr/lib/python2.7/site-packages/gunicorn/arbiter.py", line 557, in spawn_worker
worker.init_process()
File "/usr/lib/python2.7/site-packages/gunicorn/workers/base.py", line 126, in init_process
self.load_wsgi()
File "/usr/lib/python2.7/site-packages/gunicorn/workers/base.py", line 136, in load_wsgi
self.wsgi = self.app.wsgi()
File "/usr/lib/python2.7/site-packages/gunicorn/app/base.py", line 67, in wsgi
self.callable = self.load()
File "/usr/lib/python2.7/site-packages/gunicorn/app/wsgiapp.py", line 65, in load
return self.load_wsgiapp()
File "/usr/lib/python2.7/site-packages/gunicorn/app/wsgiapp.py", line 52, in load_wsgiapp
return util.import_app(self.app_uri)
File "/usr/lib/python2.7/site-packages/gunicorn/util.py", line 357, in import_app
import(module)
File "/root/flask/ansible_web/bootstrapper/bootstrap.py", line 12, in
from ec2_handler import launch_ec2_inst, list_ec2_host, gen_eip_pbook_yml, get_role_eip, create_ec2_lc
File "/root/flask/ansible_web/bootstrapper/ec2_handler.py", line 5, in
from ansible import callbacks
ImportError: cannot import name callbacks
[2017-02-10 11:03:04 +0000] [7802] [INFO] Worker exiting (pid: 7802)
[2017-02-10 11:03:04 +0000] [7797] [INFO] Shutting down: Master
[2017-02-10 11:03:04 +0000] [7797] [INFO] Reason: Worker failed to boot.