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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 import_registry(dest, src, api=None, profile=None, support=None, filter_symbol=None):
 """Imports all features and extensions and all their dependencies. :param Registry dest: Destination API :param Registry src: Source Registry :param str api: Only import Features with API name `api`, or None to import all features. :param str profile: Only import Features with profile name `profile`, or None to import all features. :param str support: Only import Extensions with this extension support string, or None to import all extensions. :param filter_symbol: Optional symbol filter callable :type filter_symbol: Callable with signature ``(symbol_type:str, symbol_name:str) -> bool`` """

    if filter_symbol is None:
        filter_symbol = _default_filter_symbol
    for x in src.get_features(api):
        import_feature(dest, src, x.name, api, profile, filter_symbol)
    for x in src.get_extensions(support):
        import_extension(dest, src, x.name, api, profile, filter_symbol)