docs: def find_all(self, pattern):
          """
          Return the subset of this RcParams dictionary whose keys match,
          using :func:`re.search`, the given ``pattern``.
  
          Parameters
          ----------
          pattern: str
              pattern as suitable for re.compile
  
          Returns
          -------
          RcParams
              RcParams instance with entries that match the given `pattern`
  
          Notes
          -----
          Changes to the returned dictionary are (different from
          :meth:`find_and_replace` are *not* propagated to the parent RcParams
          dictionary.
  
          See Also
          --------
          find_and_replace"""
          pattern_re = re.compile(pattern)
          ret = RcParams()
          ret.defaultParams = self.defaultParams
          ret.update((key, value) for key, value in self.items()
                     if pattern_re.search(key))
          return ret