'get existing info'

def get_existing(self):

    if (not self.log_dict):
        return
    if self.log_time_stamp:
        self.existing['log_time_stamp'] = self.log_dict.get('logTimeStamp').lower()
    if (self.log_buff_enable != 'no_use'):
        self.existing['log_buff_enable'] = self.log_dict.get('icLogBuffEn')
    if self.log_buff_size:
        self.existing['log_buff_size'] = self.log_dict.get('bufferSize')
    if self.module_name:
        self.existing['source'] = self.log_dict.get('source')
