Get all strips from a scraper.

def _getStrips(self, scraperobj):
        """Get all strips from a scraper."""
        if self.options.all or self.options.cont:
            numstrips = None
        elif self.options.numstrips:
            numstrips = self.options.numstrips
        else:
            # get current strip
            numstrips = 1
        try:
            if scraperobj.isComplete(self.options.basepath):
                out.info(u"All comics are already downloaded.")
                return 0
            for strip in scraperobj.getStrips(numstrips):
                skipped = self.saveComicStrip(strip)
                if skipped and self.options.cont:
                    # stop when retrieval skipped an image for one comic strip
                    out.info(u"Stop retrieval because image file already exists")
                    break
                if self.stopped:
                    break
            if self.options.all and not (self.errors or self.options.dry_run or
                                    self.options.cont or scraperobj.indexes):
                scraperobj.setComplete(self.options.basepath)
        except Exception as msg:
            out.exception(msg)
            self.errors += 1