This is a Ruby tree! It shows every object from the Ruby Programming Language in a tree format.
# Exception.cause (from ruby core) --- exception.cause -> an_exception or nil --- Returns the previous exception ($!) at the time this exception was raised. This is useful for wrapping exceptions and retaining the original exception information.
This is MURDOC! A Ruby documentation browser inspired by Smalltalk-80. It allows you to learn about Ruby by browsing through its class hierarchies, and see any of its methods.