Ingredients: 
    perfect_stat
        Parents: 
            perfect_strain
        Write:    [['write_singlerun']]
        Ready:    [['ready_singlerun']]
        Run:      [['run_singlerun']]
        Complete: [['complete_singlerun']]
        Children: 
    perfect_strain
        Parents: 
        Write:    [['write_singlerun']]
        Ready:    [['file_exists', 'POSCAR']]
        Run:      [['run_strain']]
        Complete: [['file_exists', 'CONTCAR']]
        Children: 
            perfect_stat:[['give_structure']]
