def _step3(state):
 marked = (state.marked == 1)
 state.col_uncovered[np.any(marked, axis=0)] = False
 if (marked.sum() < state.C.shape[0]):
  return _step4

def _step3 ( state ) : marked = ( state . marked == 1 ) state . col_uncovered [ np . any ( marked , axis = 0 ) ] = False if ( marked . sum ( ) < state . C . shape [ 0 ] ) : return _step4
cover each column containing a starred zero .