Comments to the code

Many useful constructs in the previous script:

• [float(arg) for arg in sys.argv[1:]] builds a list of real numbers from all the command-line arguments
• failure = os.system(cmd) runs an operating system command (e.g., another program)
• sys.exit(1) aborts the program
• ['%s_%s.png' % (method, dt) for dt in dt_values] builds a list of filenames from a list of numbers (dt_values)
• All montage commands for creating composite figures are stored in a list and thereafter executed in a loop
• glob.glob('*_*.png') returns a list of the names of all files in the current folder where the filename matches the Unix wildcard notation *_*.png (meaning "any text, underscore, any text, and then `.png`")
• os.remove(filename) removes the file with name filename