docs: def erfcc(x):
      """
  Returns the complementary error function erfc(x) with fractional
  error everywhere less than 1.2e-7.  Adapted from Numerical Recipies.
  
  Usage:   lerfcc(x)
  """
      z = abs(x)
      t = 1.0 / (1.0 + 0.5 * z)
      ans = t * math.exp(
          -z * z - 1.26551223 + t * (1.00002368 + t * (0.37409196 + t * (0.09678418 + t * (-0.18628806 + t * (0.27886807 + t * (-1.13520398 + t * (1.48851587 + t * (-0.82215223 + t * 0.17087277)))))))))
      if x >= 0:
          return ans
      else:
          return 2.0 - ans