def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def update(dt=0):
  global projpts, rgb, depth
  depth,_ = freenect.sync_get_depth()
  rgb,_ = freenect.sync_get_video()
  q = depth
  X,Y = np.meshgrid(range(640),range(480))
  # YOU CAN CHANGE THIS AND RERUN THE PROGRAM!
  # Point cloud downsampling
  d = 4
  projpts = calibkinect.depth2xyzuv(q[::d,::d],X[::d,::d],Y[::d,::d])
  refresh()