code: def down_alpha_beta(returns, factor_returns, **kwargs):
      """
      Computes alpha and beta for periods when the benchmark return is negative.
  
      Parameters
      ----------
      see documentation for `alpha_beta`.
  
      Returns
      -------
      alpha : float
      beta : float
      """
      return down(
          returns, factor_returns, function=alpha_beta_aligned, **kwargs
      )
  
imports: from __future__ import division
  import math
  import pandas
  import numpy
  from math import pow
  from scipy import stats, optimize
  from six import iteritems
  from sys import float_info
  from .utils import nanmean, nanstd, nanmin, up, down, roll, rolling_window
  from .periods import ANNUALIZATION_FACTORS, APPROX_BDAYS_PER_YEAR
  from .periods import DAILY, WEEKLY, MONTHLY, QUARTERLY, YEARLY
label_desc: Use image node_id 49 for calling a global function with example usage: down_alpha_beta(returns, factor_returns) and returns: down