Add Uncaught Exceptions In Pry as a ruby til.

README.md

@@ -131,6 +131,7 @@ smart people at [Hashrocket](http://hashrocket.com/).
 - [Rake Only Lists Tasks With Descriptions](ruby/rake-only-lists-tasks-with-descriptions.md)
 - [Squeeze Out The Extra Space](ruby/squeeze-out-the-extra-space.md)
 - [Summing Collections](ruby/summing-collections.md)
+- [Uncaught Exceptions In Pry](ruby/uncaught-exceptions-in-pry.md)
 - [`undef_method` And The Inheritance Hierarchy](ruby/undef-method-and-the-inheritance-hierarchy.md)
 
 ### tmux

ruby/uncaught-exceptions-in-pry.md

@@ -0,0 +1,21 @@
+# Uncaught Exceptions In Pry
+
+You are fiddling around with some code in a pry session trying to
+familiarize yourself with how it all works. You suddenly execute a statement
+that results in an uncaught exception. You'd like to take a closer look at
+the exception. Pry makes this easy by exposing the `_ex_` variable which
+points to the last uncaught exception.
+
+Try it out in a pry session:
+
+```ruby
+> class MyError < StandardError; end
+=> nil
+> def do_stuff; raise MyError, "Something bad happened"; end
+=> :do_stuff
+> do_stuff
+MyError: Something bad happened
+from (pry):2:in `do_stuff'
+> _ex_
+=> #<MyError: Something bad happened>
+```