add --help option

	return res.stdout

def show_help():

	print('''msp430-etv - MSP430 EnergyTrace Visualizer

USAGE

msp430-etv [--load <file> | <measurement duration>] [--save <file>]

	[--skip <count>] [--plot] [--stat]

DESCRIPTION

msp430-etv takes energy measurements from an MSP430 Launchpad or similar device

using MSP430 EnergyTrace technology. Measurements can be taken directly (by

specifying <measurement duration> in seconds) or loaded from a logfile using

--load <file>. Data can be plotted or aggregated on stdout.

OPTIONS

  --load <file>

    Load data from <file>

  --save <file>

    Save measurement data in <file>

  --skip <count>

    Skip <count> data samples. This is useful to avoid startup code

    influencing the results of a long-running measurement

  --plot

    Show power/time plot

  --stat

    Show mean voltage, current, and power as well as total energy consumption.

	''')

if __name__ == '__main__':

	try:

		optspec = ('load= save= skip= plot stat')

		optspec = ('help load= save= skip= plot stat')

		raw_opts, args = getopt.getopt(sys.argv[1:], "", optspec.split(' '))

		for option, parameter in raw_opts:

			optname = re.sub(r'^--', '', option)

			opt[optname] = parameter

		if 'help' in opt:

			show_help()

			sys.exit(0)

		if not 'load' in opt:

			duration = int(args[0])