def read_config():
    """Read configuration from file if possible."""
    # XXX modifies global state, which is kind of evil
    config = _load_config()
    if config.get(CFG_IGNORE_DEFAULT_RULES[1], False):
        del IGNORE[:]
    if CFG_IGNORE[1] in config:
        IGNORE.extend(p for p in config[CFG_IGNORE[1]] if p)
    if CFG_IGNORE_BAD_IDEAS[1] in config:
        IGNORE_BAD_IDEAS.extend(p for p in config[CFG_IGNORE_BAD_IDEAS[1]] if p)
Read configuration from file if possible.