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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 split_extension(path):
 """ A extension splitter that checks for compound extensions such as 'file.nii.gz' Parameters filename : str A filename to split into base and extension Returns ------- base : str The base part of the string, i.e. 'file' of 'file.nii.gz' ext : str The extension part of the string, i.e. 'nii.gz' of 'file.nii.gz' """

    for double_ext in double_exts:
        if path.endswith(double_ext):
            return path[:-len(double_ext)], double_ext
    dirname = os.path.dirname(path)
    filename = os.path.basename(path)
    parts = filename.split('.')
    if len(parts) == 1:
        base = filename
        ext = None
    else:
        ext = '.' + parts[-1]
        base = '.'.join(parts[:-1])
    return os.path.join(dirname, base), ext