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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def fix_trustdb(cls, trustdb=None):
 """Attempt to repair a broken trustdb.gpg file. GnuPG>=2.0.x has this magical-seeming flag: `--fix-trustdb`. You'd think it would fix the the trustdb. Hah! It doesn't. Here's what it does instead:: (gpg)~/code/python-gnupg $ gpg2 --fix-trustdb gpg: You may try to re-create the trustdb using the commands: gpg: cd ~/.gnupg gpg: gpg2 --export-ownertrust > otrust.tmp gpg: rm trustdb.gpg gpg: gpg2 --import-ownertrust < otrust.tmp gpg: If that does not work, please consult the manual Brilliant piece of software engineering right there. :param str trustdb: The path to the trustdb.gpg file. If not given, defaults to :file:`trustdb.gpg` in the current GnuPG homedir. """

    if trustdb is None:
        trustdb = os.path.join(cls.homedir, 'trustdb.gpg')
    export_proc = cls._open_subprocess(['--export-ownertrust'])
    import_proc = cls._open_subprocess(['--import-ownertrust'])
    _util._threaded_copy_data(export_proc.stdout, import_proc.stdin)
    export_proc.wait()
    import_proc.wait()