3dRprogDemo is a template program to help users write their own R
 processing routines on MRI volumes without having to deal with
 things like volume I/O or command line argument parsing.

 This template program shows rudimentary command line option parsing,
 volume reading, calling a silly processing function on each voxel time series,
 and writing the output.

 This 3dRprogDemo.R file is paired with the script 3dRprogDemo which
 allows users to run R programs directlt from the shell. To create your
 own 3dSOMETHING program you would do at least the following:

 cp 3dRprogDemo.R 3dSOMETHING.R
 cp 3dRprogDemo 3dSOMETHING
 Modify the variable ExecName in 3dSOMETHING.R to reflect your program name
 Replace the function  RprogDemo.Scale() with your own function

 Unfortunately at this stage, there is little help for the AFNI R API
 beyond this sample code. If you find yourself using this and need
 to ask questions about other dataset utility functions contact the author
 for help. The AFNIio.R file in the AFNI distribution contains most of the IO
 functions. Below are some notable ones, grep for them in the .R files for
 usage examples.

   dset.attr() for getting and setting attributes, such as the TR in seconds
               e.g. dset$NI_head <- dset.attr(dset$NI_head, "TR", val = 1.5)

   parse.AFNI.name() for parsing a filename into AFNI relevant parameters
   note.AFNI(), err.AFNI(), warn.AFNI(), exit.AFNI()

 Debugging Note:
 When running the program from the shell prompt, you cannot use R's
 browser() function to halt execution and step through the code.
 However, the utility function load.debug.AFNI.args() makes it very easy
 for you to run the command line equivalent from the R prompt. Doing so
 would make available the browser() functionality. To use load.debug.AFNI.args()
 follow these steps:
 1- Run the program from the shell command line. The program will
 automatically create a hidden file called .YOUR_PROGRAM_NAME.dbg.AFNI.args
 2- Start R from the same directory or change to the directory where
 you ran the program if you started R elesewhere
 3- Run the function:  load.debug.AFNI.args() and follow the prompts.
 The function will look for possible debug files, prompt you to pick
 the one you want, and start the execution from the R shell.

Example 1 --- Read a dataset, scale it, then write the results:
      3dRprogDemo       -input epi.nii
                        -mask mask.nii
                        -scale 7
                        -prefix toy.nii

Options in alphabetical order:

   -h_aspx: like -h_spx, with autolabeling

   -help: this help message, in simple text.

   -h_raw: this help message, as is in the code.

   -h_spx: this help message, in sphinx format

   -h_txt: this help message, in simple text

   -input DSET1                       \
      Specify the dataset to be scaled. Note that you can use
      the various sub-brick selectors used by AFNI
      e.g: -input pb05.Regression+tlrc'[face#0_Beta]'  \
      You can use multiple instances of -input in one command line
      to process multiple datasets in the same manner.

   -mask MASK: Process voxels inside this mask only.
             Default is no masking.

   -prefix PREFIX: Output prefix (just prefix, no view+suffix needed)

   -scale SS: Multiply each voxel by SS

   -show_allowed_options: list of allowed options

   -verb VERB: VERB is an integer specifying verbosity level.
             0 for quiet (Default). 1 or more: talkative.