Vendor/phpspreadsheet/phpoffice/phpspreadsheet/src/PhpSpreadsheet/Calculation/Functions.php
public static function isNumber($value = null)
    {
        $value = self::flattenSingleValue($value);

        if (is_string($value)) {
            return false;
        }

        return is_numeric($value);
    }
public static function isNumber($value = null)
    {
        $value = self::flattenSingleValue($value);

        if (is_string($value)) {
            return false;
        }

        return is_numeric($value);
    }
public static function isNumber ( $ value = null ) { $ value = self :: flattenSingleValue ( $ value ) ; if ( is_string ( $ value ) ) { return false ; } return is_numeric ( $ value ) ; }
IS_NUMBER.

@param mixed $value Value to check

@return bool
IS_NUMBER .