def _env_pairs_to_dict(ctx, param, value):
    """Converts a space-seperated list of key=value pairs into a Python
    dictionary.
    """
    d = {}
    for pair in [x.split('=', 1) for x in value]:
        if len(pair) == 1:
            d[pair[0]] = ''
        else:
            d[pair[0]] = pair[1]
    return d