docs: def get_pattern_mat(oracle, pattern):
      """Output a matrix containing patterns in rows from a vmo.
  
      :param oracle: input vmo object
      :param pattern: pattern extracted from oracle
      :return: a numpy matrix that could be used to visualize the pattern extracted.
      """
  
      pattern_mat = np.zeros((len(pattern), oracle.n_states-1))
      for i,p in enumerate(pattern):
          length = p[1]
          for s in p[0]:
              pattern_mat[i][s-length:s-1] = 1
      
      return pattern_mat