def get_exchange_reactions(model):
for reaction_id in model.reactions:<EOL><INDENT>if model.is_exchange(reaction_id):<EOL><INDENT>yield reaction_id<EOL><DEDENT><DEDENT>
Yield IDs of all exchange reactions from model.

    This helper function would be useful when creating
    :class:`.ReactionDeletionStrategy` objects.

    Args:
        model: :class:`psamm.metabolicmodel.MetabolicModel`.