Can't run xflux in Ubuntu

Question

I have already installed xflux. But when i run fluxgui in command line it says:fluxgui

Traceback (most recent call last):
  File "/usr/local/bin/fluxgui", line 17, in <module>
    from fluxgui.fluxapp import main
  File "/usr/local/lib/python2.7/dist-packages/fluxgui/fluxapp.py", line 3, in <module>
    from fluxgui import fluxcontroller, settings
  File "/usr/local/lib/python2.7/dist-packages/fluxgui/fluxcontroller.py", line 1, in <module>
    from fluxgui import xfluxcontroller
  File "/usr/local/lib/python2.7/dist-packages/fluxgui/xfluxcontroller.py", line 1, in <module>
    import pexpect
ImportError: No module named pexpect

I am using Ubuntu 16.04.3 LTS 64-bit Is there any better alternative to programs like xflux? My eyes strain while not using it.