# CORRECT
async def async_fetch_user(user_id: int) -> User:
    return await client.get(f"/users/{user_id}")

async def async_process_batch(items: list[Item]) -> list[Result]:
    return await asyncio.gather(*[async_process(item) for item in items])

# INCORRECT - missing async_ prefix
async def fetch_user(user_id: int) -> User:  # Bad: not clear await is needed
    ...

# CORRECT
user_count = len(users)
max_retry_attempts = 3
embedding_dimensions = 768
is_authenticated = True
has_valid_license = check_license(user)

# INCORRECT
data = len(users)      # Too generic
n = 3                  # Single letter

# CORRECT
class SearchIndex: ...
class EmbeddingModel: ...
class RetryPolicy: ...
class ValidationError: ...

# INCORRECT
class Search: ...          # Verb-like, unclear purpose
class EmbModel: ...        # Abbreviation
class DoValidation: ...    # Verb phrase

from typing import Final

# CORRECT
MAX_RETRY_ATTEMPTS: Final = 3
DEFAULT_TIMEOUT_SECONDS: Final[float] = 30.0
SUPPORTED_FILE_FORMATS: Final[frozenset[str]] = frozenset({"json", "csv", "parquet"})

# INCORRECT
MaxRetries = 3              # Wrong case, missing Final
max_retry_attempts = 3      # Wrong case for constant
MAX_RETRY_ATTEMPTS = 3      # Missing Final annotation

class SearchService:
    def __init__(self, index: VectorIndex) -> None:
        self._index = index              # Private attribute
        self._cache: dict[str, Result] = {}  # Private attribute

    def search(self, query: str) -> list[Result]:  # Public API
        return self._perform_search(query)

    def _perform_search(self, query: str) -> list[Result]:  # Private method
        ...

# CORRECT
JsonValue = dict[str, Any] | list[Any] | str | int | float | bool | None
Embedding = list[float]
UserId = int

# INCORRECT
json_value = dict[str, Any] | list[Any] | str | int | float | bool | None  # Wrong case