def dev_log_level
      if value = tag_value(LOG_LEVEL_TAG)
        value = value.downcase.to_sym
        value = nil unless [:debug, :info, :warn, :error, :fatal].include?(value)
      end
      value
    end
def dev_log_level
      if value = tag_value(LOG_LEVEL_TAG)
        value = value.downcase.to_sym
        value = nil unless [:debug, :info, :warn, :error, :fatal].include?(value)
      end
      value
    end
Determines the developer log level, if any, which forces and supercedes
 all other log level configurations.

 === Return
 level(Token):: developer log level or nil