Class Trace

@param count true iff it should count number of times each
             line is executed
@param trace true iff it should print out each line that is
             being counted
@param countfuncs true iff it should just output a list of
             (filename, modulename, funcname,) for functions
             that were called at least once;  This overrides
             `count' and `trace'
@param ignoremods a list of the names of modules to ignore
@param ignoredirs a list of the names of directories to ignore
             all of the (recursive) contents of
@param infile file from which to read stored counts to be
             added into the results
@param outfile file in which to write the results

Handler for call events.

Adds information about who called who to the self._callers dict.

Handler for call events.

Adds (filename, modulename, funcname) to the self._calledfuncs dict.

Handler for call events.

If the code block being entered is to be ignored, returns `None', else returns self.localtrace.