For Statment Question

[shanenin]

I am trying to figure out what is happening in the following code

def main(argv):                          
    grammar = "kant.xml"                
    try:                                
    except getopt.GetoptError:          
        usage()                         
        sys.exit(2)                     
    for opt, arg in opts:                
        if opt in ("-h", "--help"):      
            usage()                     
            sys.exit()                  
        elif opt == '-d':                
            global _debug               
            _debug = 1                  
        elif opt in ("-g", "--grammar"): 
            grammar = arg

in particular this line

for opt, arg in opts:

when ever I try to use similar syntax in my python interpreter I get this error

>>> opts = ['j','h','f']
>>> for i, y in opts:
...  print i
...
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
ValueError: need more than 1 value to unpack

[jcl]

opts is probably a list of pairs, e.g. [('foo', 'bar'), ('baz', 'fnord')].

Edited August 29, 2005 by jcl