'Ensure feature and its requirements are included in distribution
You may override this in a subclass to perform additional operations on
the distribution.  Note that this method may be called more than once
per feature, and so should be idempotent.'

def include_in(self, dist):

    if (not self.available):
        raise DistutilsPlatformError((self.description + '    is    required,but    is    not    available    on    this    platform'))
    dist.include(**self.extras)
    for f in self.require_features:
        dist.include_feature(f)
