Could you give an example of implementing the dependency inversion principle in code?

The Dependency Inversion Principle states that high-level modules should not depend on low-level modules; both should depend on abstractions (such as interfaces or abstract classes). In Python, this can be implemented through dependency injection via constructors or methods.

Example:

from abc import ABC, abstractmethod

class Database(ABC):
    @abstractmethod
    def save(self, data):
        pass

class MySQLDatabase(Database):
    def save(self, data):
        print(f"Saving {data} to MySQL")

class UserService:
    def __init__(self, db: Database):
        self.db = db

    def create_user(self, user_data):
        # business logic
        self.db.save(user_data)

# Usage
mysql_db = MySQLDatabase()
service = UserService(mysql_db)
service.create_user({'name': 'Ivan'})

Here, UserService depends not on a specific database implementation but on the abstraction Database. This makes it easier to replace implementations and for testing.