def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
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()