Turn a Python code base into a web application

I have built a code base for a financial calculator in Python 3. Inside the code, libraries (pandas,numpy,prophet,etc.) are imported, financial functions are defined, and an operation guideline (while True,try,except,etc.) is also defined for user inputs. If I run the code, input boxes will appear and users only need to follow the guideline to get to the desired results.

My question is how can I turn this into a web application that internet users can access? I have looked at some flask tutorials but they only touch on hello-world types of application which are too simple for my purpose. For example, flask flags the error "invalid syntax" for my "import pandas as pd". Does it mean I'm not allowed to import libraries in flask? Sorry for my shallow knowledge in this domain. Please enlighten me...