code: def _mkanchors(ws, hs, x_ctr, y_ctr):
          
          ws = ws[:, np.newaxis]
          hs = hs[:, np.newaxis]
          anchors = np.hstack((x_ctr - 0.5 * (ws - 1),
                               y_ctr - 0.5 * (hs - 1),
                               x_ctr + 0.5 * (ws - 1),
                               y_ctr + 0.5 * (hs - 1)))
          return anchors
docs: Given a vector of widths (ws) and heights (hs) around a center
          (x_ctr, y_ctr), output a set of anchors (windows).