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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_command(dest, src, name, api=None, filter_symbol=None):
 """Import Command `name` and its dependencies from Registry `src` to Registry `dest` :param Registry dest: Destination Registry :param Registry src: Source Registry :param str name: Name of Command to import :param str api: Prefer to import Types with api name `api`, or None to import Types with no api name :param filter_symbol: Optional filter callable :type filter_symbol: Callable with signature ``(symbol_type:str, symbol_name:str) -> bool`` """

    if not filter_symbol:
        filter_symbol = _default_filter_symbol
    cmd = src.commands[name]
    for x in cmd.required_types:
        if not filter_symbol('type', x):
            continue
        import_type(dest, src, x, api, filter_symbol)
    dest.commands[name] = cmd