cheat sheets.

--- exceptions version 2	Sat Sep 12 06:27:23 -0700 2009
+++ exceptions version 4	Sun Nov 13 08:24:38 -0800 2011
@@ -1,30 +1,32 @@
 Exception
  NoMemoryError
  ScriptError
    LoadError
    NotImplementedError
    SyntaxError
  SignalException
    Interrupt
      Timeout::Error    # require 'timeout' for Timeout::Error
  StandardError         # caught by rescue if no type is specified
    ArgumentError
    IOError
      EOFError
    IndexError
    LocalJumpError
    NameError
      NoMethodError
    RangeError
      FloatDomainError
    RegexpError
    RuntimeError
+     Timeout::Error    # moved here in ruby 1.9.2
    SecurityError
+   SocketError
    SystemCallError
    SystemStackError
    ThreadError
    TypeError
    ZeroDivisionError
  SystemExit
  fatal