SQL alchemy split project into different files - import

Question

I am implementing simple database, right now my goal is to split project into different modules, as it should be done. So far, my project consists of bunch of files:
base.py
from sqlalchemy.orm import declarative_base
Base = declarative_base()
file implementing tables
classes.py
from sqlalchemy import Column, Integer, String, Date, ForeignKey
from sqlalchemy.orm import relationship, validates
from base import Base
class Book(Base):
...
class Owner(Base):
...
creation of engine, session, etc
database.py
from sqlalchemy import create_engine
from sqlalchemy.orm import Session
from datetime import date
from base import Base
engine = create_engine("sqlite+pysqlite:///mydb.db")
session = Session(engine)
from operations import *
import parser_file
Base.metadata.create_all(engine)
if __name__ == '__main__':
parser_file.main()
Here I import session from database.py
operations.py
from classes import Book, Owner
from database import session
def add_book(title, author, year_published=None):
...
# and many more
parser_file.py
import argparse
from datetime import date
from operations import *
def main():
...
I am not sure about the imports. operations.py, parser_file.py and database.py all import from each other. It used to throw error, but i moved from operations import * and import parser_file after creation of Session. It feels sketchy having imports in the middle of the code as I am used to imports on top of file, and on some posts there are people mentioning that modules should not depend on each other. On the other hand, the code is now nicely split and it feels better this way. What is the correct way to handle these?
Edit: From PEP8 guide on imports
Imports are always put at the top of the file, just after any module comments and docstrings, and before module globals and constants
So it seems like what I did is considered bad.