but what is if/else expression we need to write to get the values from the previous task,

i tried with "tasks.previous_task_name.values.value_of_previous_task" =="SUCCESS" in the expression. throwing an error task value referenced by  tasks.<previous_task>.values.value was not found.

i tried to declare/set a custom status by using these approaches.

1) dbutils.notebook.exit({status:"success"})  2) dbutils.job.taskValues.get(key="status",values ="success")

Need your help to write if/else expression to get the value. 

Thanks !!!