Customize help output from optparse (or argparse)

[Thorsten Kampe]

Hi, 

I'm using optparse for a little Python script.

1. The output from "--help" is:
"""
Usage: script.py <arg>

script.py does something

Options:
  -h, --help   show this help message and exit
"""

I would prefer to have the description before the usage, like...
"""
script.py does something

Usage: script.py <arg>

Options:
  -h, --help   show this help message and exit
"""

2. The output from "--doesnotexit" is:
"""
Usage: script.py <arg>

script.py: error: no such option: --doesnotexist
"""

I would prefer to have the error first, then the usage and additionally 
the options, like...
"""
script.py: error: no such option: --doesnotexist

Usage: script.py <arg>

Options:
  -h, --help   show this help message and exit
"""

Is that possible with either optparse or the "new kid on the block" 
argparse. If so how?

Thorsten