I need someone who can write python code to accept the csv file as a data and do massaging on it.

I am looking for a freelancer experienced in Python to help me with a project. My goal is to be able to accept a CSV file as a data input, and then do further massaging on the data. Specifically, I am looking for someone to merge and transform the data. The data is complex, and includes nested data structures, missing data, and large datasets. I am open to using any specific Python libraries or frameworks that are necessary to accomplish this task.