Return a dictionary containing the key/values read from filename.

        Raises IOError if the file does not exit etcetera.

def _actually_populate_keyvals(filename):
        """Return a dictionary containing the key/values read from filename.

        Raises IOError if the file does not exit etcetera.

        """
        assert isinstance(filename, str)
        keyvals = {}
        with open(filename, 'r') as f:
            for line in f:
                line = line.strip("\r\n")
                pieces = line.split(_KeyValuePersister._delimiter)
                if len(pieces) >= 2:
                    key = pieces[0]
                    val = _KeyValuePersister._delimiter.join(pieces[1:])
                    keyvals[key] = val
        return keyvals