Update guide.md (google#31)

Jackevansevo · dbieber · commit 35a3ec9981a3 · 2017-03-23T11:30:39.000-07:00
Python Fire Guide: Fix "NameError: name 'x' is not defined" in Argument Parsing example
diff --git a/doc/guide.md b/doc/guide.md
@@ -567,7 +567,7 @@ of any argument we give it:
 
 ```python
 import fire
-fire.Fire(lambda obj: type(x).__name__)
+fire.Fire(lambda obj: type(obj).__name__)
 ```
 
 And we'll use it like so:
