# echo 'task goes here' | cat - todo.txt > temp && mv temp todo.txt



A=`ls *.py`

for a in $A;  do 
echo $a;

mv  $a tmp_${a}

# echo '#!/usr/bin/env python3' >> $a

echo '#!/usr/bin/env python3' | cat - tmp_${a} > $a 


diff $a tmp_${a}
echo '-----------------------------'; echo 

 done