# File lib/dbi/handles.rb, line 21
        def trace(mode=nil, output=nil)
            # FIXME trace
            raise InterfaceError, "the trace module has been removed until it actually works."
            @trace_mode   = mode   || @trace_mode   || DBI::DEFAULT_TRACE_MODE
            @trace_output = output || @trace_output || DBI::DEFAULT_TRACE_OUTPUT
        end