public function getHashAlgorithmParameter(File $phpcsFile, $stackPtr)
    {
        $tokens = $phpcsFile->getTokens();

        // Check for the existence of the token.
        if (isset($tokens[$stackPtr]) === false) {
            return false;
        }

        if ($tokens[$stackPtr]['code'] !== \T_STRING) {
            return false;
        }

        $functionName   = $tokens[$stackPtr]['content'];
        $functionNameLc = strtolower($functionName);

        // Bow out if not one of the functions we're targetting.
        if (isset($this->hashAlgoFunctions[$functionNameLc]) === false) {
            return false;
        }

        // Get the parameter from the function call which should contain the algorithm name.
        $algoParam = $this->getFunctionCallParameter($phpcsFile, $stackPtr, $this->hashAlgoFunctions[$functionNameLc]);
        if ($algoParam === false) {
            return false;
        }

        // Algorithm is a text string, so we need to remove the quotes.
        $algo = strtolower(trim($algoParam['raw']));
        $algo = $this->stripQuotes($algo);

        return $algo;
    }