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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 _normalize_roots(file_roots):
    '''
    Normalize file or pillar roots.
    '''
    for saltenv, dirs in six.iteritems(file_roots):
        normalized_saltenv = six.text_type(saltenv)
        if normalized_saltenv != saltenv:
            file_roots[normalized_saltenv] = file_roots.pop(saltenv)
        if not isinstance(dirs, (list, tuple)):
            file_roots[normalized_saltenv] = []
        file_roots[normalized_saltenv] = \
                _expand_glob_path(file_roots[normalized_saltenv])
    return file_roots