code: def proj_transform(xs, ys, zs, M):
      """
      Transform the points by the projection matrix *M*.
      """
      vec = _vec_pad_ones(xs, ys, zs)
      return _proj_transform_vec(vec, M)
  
imports: import numpy
  from matplotlib import _api
label_desc: Use image node_id 15 for calling a global function with example usage: proj_transform(xs, ys, zs, M) and returns: _proj_transform_vec