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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def validate_path(ctx, param, value):
 """Detect a workflow path if it is not passed."""

    client = ctx.obj

    if value is None:
        from renku.models.provenance import ProcessRun
        activity = client.process_commit()

        if not isinstance(activity, ProcessRun):
            raise click.BadParameter('No tool was found.')

        return activity.path

    return value