# import warnings

**[import warnings](https://docs.python.org/3/library/warnings.html)** is a Python import that issues warning messages. Use it to alert users about deprecated features or suspicious code without raising exceptions.

## Example

```python
# Python
# description: issue and filter warnings

import warnings

# Issue a warning
warnings.warn("This feature is deprecated", DeprecationWarning)

# Suppress warnings temporarily
with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    # Code that issues warnings runs silently
    warnings.warn("This warning is suppressed")

# Filter warnings globally
warnings.simplefilter("always")  # show all warnings
warnings.simplefilter("ignore")  # ignore all warnings
warnings.simplefilter("error")   # convert to exceptions

# Custom warning category
class CustomWarning(UserWarning):
    pass

warnings.warn("Custom issue", CustomWarning)
```

## Common functions

- `warnings.warn(message, category)`: issue warning
- `warnings.simplefilter(action)`: filter warnings
  - "always" — always print
  - "ignore" — suppress
  - "error" — convert to exception
  - "once" — print once per location
- `warnings.catch_warnings()`: context manager for temporary filtering
- Warning categories: `UserWarning`, `DeprecationWarning`, `SyntaxWarning`