Remove all files and directories in the working directory

        Args:
            exclude_wildcard: Optional string with regular expressions separated by `|`.
                Files matching one of the regular expressions will be preserved.
                example: exclude_wildard="*.nc|*.txt" preserves all the files
                whose extension is in ["nc", "txt"].

def rmtree(self, exclude_wildcard=""):
        """
        Remove all files and directories in the working directory

        Args:
            exclude_wildcard: Optional string with regular expressions separated by `|`.
                Files matching one of the regular expressions will be preserved.
                example: exclude_wildard="*.nc|*.txt" preserves all the files
                whose extension is in ["nc", "txt"].
        """
        if not exclude_wildcard:
            shutil.rmtree(self.workdir)

        else:
            w = WildCard(exclude_wildcard)
            for dirpath, dirnames, filenames in os.walk(self.workdir):
                for fname in filenames:
                    path = os.path.join(dirpath, fname)
                    if not w.match(fname):
                        os.remove(path)