`select parseDateTimeBestEffort('01/12/2017, 18:31:44')`

It is confused by a comma - should be easy to fix.
{
                    if (day_of_month)
                        return on_error("Cannot read DateTime: day of month is duplicated", ErrorCodes::CANNOT_PARSE_DATETIME);
                    if (month)
                        return on_error("Cannot read DateTime: month is duplicated", ErrorCodes::CANNOT_PARSE_DATETIME);
                    if constexpr (is_us_style)
                    {
                        month = hour_or_day_of_month_or_month;
                        num_digits = readDigits(digits, sizeof(digits), in);
                        if (num_digits == 2)
                            readDecimalNumber<2>(day_of_month, digits);
                        else if (num_digits == 1)
                            readDecimalNumber<1>(day_of_month, digits);
                        else
                            return on_error("Cannot read DateTime: unexpected number of decimal digits after month: " + toString(num_digits), ErrorCodes::CANNOT_PARSE_DATETIME);
                    }
                    else
                    {
                        day_of_month = hour_or_day_of_month_or_month;
                        num_digits = readDigits(digits, sizeof(digits), in);
                        if (num_digits == 2)
                            readDecimalNumber<2>(month, digits);
                        else if (num_digits == 1)
                            readDecimalNumber<1>(month, digits);
                        else if (num_digits == 0)
                        {
                           
                          char alpha[9];  
                          size_t num_alpha = readAlpha(alpha, sizeof(alpha), in);
                          if (num_alpha < 3)