input: Write a python function to filter email addresses that end with "@gmail.com".
  assert filter_gmail(["john@gmail.com", "sophie@gmail.com", "alex@yahoo.com", "maria@hotmail.com"]) == ["john@gmail.com", "sophie@gmail.com"]
  assert filter_gmail(["bob@yahoo.com", "alice@gmail.com", "charlie@gmail.com", "dave@outlook.com"]) == ["alice@gmail.com", "charlie@gmail.com"]
  assert filter_gmail(["john@yahoo.com", "sophie@outlook.com", "alex@hotmail.com", "maria@aol.com"]) == []
output: def filter_gmail(emails):
      return [email for email in emails if email.endswith("@gmail.com")]