def add_reaction(self, reaction_id):
if reaction_id in self._reaction_set:<EOL><INDENT>return<EOL><DEDENT>reaction = self._database.get_reaction(reaction_id)<EOL>self._reaction_set.add(reaction_id)<EOL>for compound, _ in reaction.compounds:<EOL><INDENT>self._compound_set.add(compound)<EOL><DEDENT>
Add reaction to model