| Arg abstract base class specialized for exactly one parameter.    Members:
        argnameThe name of the keyword argument used to pass
            this argument to Python.        defaultThe default value of the argument, used if no
            keyword parameter is found.  If this is None, then no
            default is assumed. 
        
            | Methods |  |  
        | __init__ get_option
 
 |  
            |  | __init__ |  
        | 
__init__ (
        self,
        argname,
        default,
        )
 |  
            |  | get_option |  
        | 
get_option ( self,  keyw )
 Get the keyword argument corresponding to this Arg.        Look in keyw for the keyword argument needed by this Arg.  If
        it is found, delete it from keyw and return it.  If it is not
        found, return self.default. |  |