setTimestampFormat.Verbose: Sets the default timestamp format
Description
  Sets the default timestamp format.
Usage
"setTimestampFormat"(this, format="%Y%m%d %H:%M:%S|", ...)
Arguments
format
If a function, this function is called (without arguments)
   whenever a timestamp is generated. If a character string, it used as
   the format string in format(Sys.date(), fmt). Value
  Returns (invisibly) the old timestamp format.