code: def _smoothing(precision_fractions, c=1):
      
      ratios = [0] * len(precision_fractions)
      for i, precision_fraction in enumerate(precision_fractions):
          if precision_fraction[1] > 0:
              ratios[i] = float(precision_fraction[0] + c) / (precision_fraction[1] + c)
          else:
              ratios[i] = 0.0
  
      return ratios
docs: Compute the smoothed precision for all the orders.
  
      Parameters
      ----------
      precision_fractions: list(tuple)
          Contain a list of (precision_numerator, precision_denominator) pairs
      c: int, default 1
          Smoothing constant to use
  
      Returns
      -------
      ratios: list of floats
          Contain the smoothed precision_fractions.