In your /PATH/Python-2.7.x/Lib should be all your modules, incl. future
If you don't have the above, re-install Python.
If you do, run ls -l which will show you the permissions associated with the modules in the first column. *.py should read -rwxr-xr-x. If it reads -rw-r--r-- instead, the modules can't be imported or executed when they are called in your script. To fix this, change permissions with sudo chmod +x *.py.
Also, you need to check that python knows where to look for these modules. You can check this with echo $PYTHONPATH which should show you the path to you Lib directory. If not, set via export PYTHONPATH=$PYTHONPATH:/PATH/Python-2.7.13/Lib.