docs: def write_reactions(self, stream, reactions, properties=None):
          """Write iterable of reactions as YAML object to stream.
  
          Args:
              stream: File-like object.
              compounds: Iterable of reaction entries.
              properties: Set of reaction properties to output (or None to output
                  all).
          """
          self._write_entries(
              stream, reactions, self.convert_reaction_entry, properties)