'Print a summary of errors by category, and the total.'

def PrintErrorCounts(self):

    for (category, count) in sorted(iteritems(self.errors_by_category)):
        self.PrintInfo(("Category    '%s'    errors    found:    %d\n" % (category, count)))
    if (self.error_count > 0):
        self.PrintInfo(('Total    errors    found:    %d\n' % self.error_count))
