<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def textile(value):
 """ Textile processing. """

    try:
        import textile
    except ImportError:
        warnings.warn("The Python textile library isn't installed.",
                      RuntimeWarning)
        return value

    return textile.textile(force_text(value))