class RSpec::Core::Configuration

def cleaned_from_backtrace?(line)

or not, based on the line matching any `backtrace_clean_patterns`.
Used by formatters to ask whether a backtrace line should be displayed 
def cleaned_from_backtrace?(line)
  # TODO (David 2011-12-25) why are we asking the configuration to do
  # stuff? Either use the patterns directly or enapsulate the filtering
  # in a BacktraceCleaner object.
  backtrace_clean_patterns.any? { |regex| line =~ regex }
end