How to generate rows based on values in a column to fill missing values

[codesmatter]

I'm trying to generate new rows based on values in a certain column. In current data as you can see 'days_left' column does not have all sequential values.

current = {'assignment': [1,1,1,1,2,2,2,2,2], 'days_left': [1, 2, 5, 9,1, 3, 4, 8, 13]}
dfcurrent = pd.DataFrame(data=current)
dfcurrent


While I want to generate rows into that dataframe to create make sequential list for for 'days_left' for each 'assignment'. Please see the desidered output below:


desired = {'assignment': [1,1,1,1,1,1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2],
'days_left': [1,2,3,4,5,6,7,8,9,1,2,3,4,5,6,7,8,9,10,11,12,13]}
dfdesired = pd.DataFrame(data=desired)
dfdesired


Note: The original data is much bigger and has other columns as well but I just simplified it for this question.

Could you please help me how I can solve this?

Thank you very much in advance!

[Larz60+]

Please note that you need to make an effort, we will be glad to help, but cannot write it for you.
Give it a go, and come back with specific questions when (and if) you run into a problem.