clean up unused Python imports (#454)

* Remove unused python imports

These changes have been auto-generated with:

	pip3 install isort autoflake
	isort -rc -sl .
	autoflake --remove-all-unused-imports -i -r .
	isort -rc -m 3 .

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

* python: remove redundant parenthesis

Signed-off-by: Radostin Stoyanov <rstoyanov@fedoraproject.org>

exercises/link_monitor/send.py

@@ -1,8 +1,10 @@
 #!/usr/bin/env python3
 import sys
 import time
+
 from probe_hdrs import *
 
+
 def main():
 
     probe_pkt = Ether(dst='ff:ff:ff:ff:ff:ff', src=get_if_hwaddr('eth0')) / \