code: def add(self, labels, value):
          
  
          if type(value) not in (float, int):
              raise TypeError("Summary only works with digits (int, float)")
  
          # We have already a lock for data but not for the estimator
          with mutex:
              try:
                  e = self.get_value(labels)
              except KeyError:
                  # Initialize quantile estimator
                  e = quantile.Estimator(*self.__class__.DEFAULT_INVARIANTS)
                  self.set_value(labels, e)
              e.observe(float(value))
docs: Add adds a single observation to the summary.