code: def get_zeta_i_j_given_separate_counts(self, y_i, y_j):
  		'''
  		Parameters
  		----------
  		y_i, np.array(int)
  			Arrays of word counts of words occurring in positi ve class
  		y_j, np.array(int)
  
  		Returns
  		-------
  		np.array of z-scores
  		'''
  		n_i, n_j = y_i.sum(), y_j.sum()
  		delta_i_j = (np.log((y_i + 1) / (1. + n_i - y_i))
  		             - np.log((y_j + 1) / (1. + n_j - y_j)))
  		return delta_i_f get_zeta_i_j_given_separate_counts(self, y_i, y_j):
  		'''
  		Parameters
  		----------
  		y_i, np.array(int)
  			Arrays of word counts of words occurring in positi ve class
  		y_j, np.array(int)
  
  		Returns
  		-------
  		np.array of z-scores
  		'''
  		n_i, n_j = y_i.sum(), y_j.sum()
  		delta_i_j = (np.log((y_i + 1) / (1. + n_i - y_i))
  		             - np.log((y_j + 1) / (1. + n_j - y_j)))
  		return delta_i_j
docs: Parameters
  		----------
  		y_i, np.array(int)
  			Arrays of word counts of words occurring in positi ve class
  		y_j, np.array(int)
  
  		Returns
  		-------
  		np.array of z-scores