Impute missing values without leakage

You are preparing a user-level event dataset for model training and must fill in missing values without leaking any information from the validation data into the training statistics. You are given a pandas DataFrame df with these columns: column type user_id user identifier event_date datetime country categorical device_type categorical age numeric income numeric last_purchase_days_ago numeric session_length numeric is_active_30d binary label Implement code that imputes the…