PP(pp_study)
{
    dVAR; dSP; dPOPss;
    STRLEN len;

    (void)SvPV(sv, len);
    if (len == 0 || len > I32_MAX || !SvPOK(sv) || SvUTF8(sv) || SvVALID(sv)) {
	/* Historically, study was skipped in these cases. */
	RETPUSHNO;
    }

    /* Make study a no-op. It's no longer useful and its existence
       complicates matters elsewhere. */
    RETPUSHYES;
}