code: def relative_to(base, relativee):
      
      basepath = os.path.abspath(base)
      relativee = os.path.abspath(relativee)
      if relativee.startswith(basepath):
          relative = relativee[len(basepath):]
          if relative.startswith(os.sep):
              relative = relative[1:]
          return os.path.join(base, relative)
      raise ValueError("%s is not a subpath of %s" % (relativee, basepath))
docs: Gets 'relativee' relative to 'basepath'.
  
      i.e.,
  
      >>> relative_to('/home/', '/home/radix/')
      'radix'
      >>> relative_to('.', '/home/radix/Projects/Twisted') # curdir is /home/radix
      'Projects/Twisted'
  
      The 'relativee' must be a child of 'basepath'.