<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def configured_class(cls):
 # type: () -> type """Returns the currently configured class."""

        base = cls.configurable_base()
        # Manually mangle the private name to see whether this base
        # has been configured (and not another base higher in the
        # hierarchy).
        if base.__dict__.get('_Configurable__impl_class') is None:
            base.__impl_class = cls.configurable_default()
        return base.__impl_class