class Guard::Internals::Debugging

def start

* traces execution of Kernel.system and backtick calls
* Set the logging level to `:debug`
* aborts on thread exceptions

Sets up debugging: 
def start
  return if @started ||= false
  @started = true
  Thread.abort_on_exception = true
  UI.level = Logger::DEBUG
  TRACES.each { |mod, meth| _trace(mod, meth, &method(:_notify)) }
  @traced = true
end