[python] [patch] Add is_valid to several classes

[Paul Koning]

On Mar 16, 2011, at 3:22 PM, Eli Zaretskii wrote:

>> From: Phil Muldoon <pmuldoon@redhat.com>
>> Date: Wed, 16 Mar 2011 16:02:44 +0000
>> ...
> 
>> +@defmethod Inferior is_valid
>> +Returns true if the @code{gdb.Inferior} object is valid, false if
>           ^^^^                                             ^^^^^
> You mean @code{true} and @code{false}, right?  These are Python
> symbols, aren't they?

Actually, the Python symbols are @code{True} and @code{False} (first letter uppercase).  It would make sense to write it that way whenever the Python bool values are referenced.

	paul