argparse feature request

[Neal Becker]

I use arparse all the time and find it serves my needs well.  One thing I'd like 
to see.  In the help message, I'd like to automatically add the default values.

For example, here's one of my programs:

 python3 test_freq3.py --help
usage: test_freq3.py [-h] [--size SIZE] [--esnodB ESNODB] [--tau TAU] [--trials 
TRIALS]
                     [--training TRAINING] [--sps SPS] [--si SI] [--alpha ALPHA]
                     [--range RANGE] [--dfunc {gradient,delay}]
                     [--mod 
{gaussian,qpsk,8psk,16apsk,32apsk,32dlr,64apsk,256apsk}]
                     [--sym-freq-err SYM_FREQ_ERR] [--calibrate [CALIBRATE]]

optional arguments:
  -h, --help            show this help message and exit
  --size SIZE
  --esnodB ESNODB, -e ESNODB
  --tau TAU, -t TAU
  --trials TRIALS
  --training TRAINING
  --sps SPS
  --si SI
  --alpha ALPHA
  --range RANGE
  --dfunc {gradient,delay}
  --mod {gaussian,qpsk,8psk,16apsk,32apsk,32dlr,64apsk,256apsk}
  --sym-freq-err SYM_FREQ_ERR
  --calibrate [CALIBRATE], --with-calibrate [CALIBRATE], --enable-calibrate 
[CALIBRATE], --no-calibrate [CALIBRATE], --without-calibrate [CALIBRATE], --
disable-calibrate [CALIBRATE]

What I'd like to see is:

--size SIZE [2000]  <<< the default value is displayed