public function leastCheck(float $valence, array $tokens, int $index) : float
    {
        if($index === 0) {
            return $valence;
        }
        
        $inLexicon = isset($this->getLexicon()[strtolower($tokens[$index-1])]);
        
        if($inLexicon) {
            return $valence;                       
        }
        
        $leastIndex = array_searchi('least', $tokens);
        $atIndex = array_searchi('at', $tokens);
        $veryIndex = array_searchi('very', $tokens);
        
        if($leastIndex == $index-1 && $atIndex != $index-2 && $veryIndex != $index-2) {
            $valence *= self::N_SCALAR;
        } elseif( $leastIndex == $index-1) {
            $valence *= self::N_SCALAR;
        }
        
        return $valence;  
    }