<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def warn_deprecated(message, stacklevel=2):
 # pragma: no cover """Warn deprecated."""


    warnings.warn(
        message,
        category=DeprecationWarning,
        stacklevel=stacklevel
    )