code: def downmarket_filter(
          self,
          benchmark,
          threshold=0.0,
          compare_op="lt",
          include_benchmark=False,
      ):
          
  
          return self._mkt_filter(
              benchmark=benchmark,
              threshold=threshold,
              compare_op=compare_op,
              include_benchmark=include_benchmark,
          )
docs: Drop elementwise samples where `benchmark` > `threshold`.
  
          Filters `self` (and optionally, `benchmark`) to periods
          where `benchmark` < `threshold`.  (Or <= `threshold`.)
  
          Parameters
          ----------
          benchmark : {pd.Series, TSeries, 1d np.ndarray}
              The benchmark security to which `self` is compared.
          threshold : float, default 0.0
              The threshold at which the comparison should be done.
              `self` and `benchmark` are "filtered" to periods where
              `benchmark` is lt/le `threshold`.
          compare_op : {'lt', 'le'}
              Comparison operator used to compare to `threshold`.
              'lt' is less-than; 'le' is less-than-or-equal.
          include_benchmark : bool, default False
              If True, return tuple of (`self`, `benchmark`) both
              filtered.  If False, return only `self` filtered.
  
          Returns
          -------
          TSeries or tuple of TSeries
              TSeries if `include_benchmark=False`, otherwise, tuple.