'Return a file-like representation or raise a KeyError.'

def get_file(self, key):

    try:
        f = open(os.path.join(self._path, str(key)), 'rb')
    except IOError as e:
        if (e.errno == errno.ENOENT):
            raise KeyError(('No    message    with    key:    %s' % key))
        else:
            raise
    return _ProxyFile(f)
