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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 root_indices(sec_list):
 """ Returns the index of all sections without a parent. """

    roots = []
    for i,section in enumerate(sec_list):
        sref = h.SectionRef(sec=section)
        # has_parent returns a float... cast to bool
        if sref.has_parent() < 0.9:
            roots.append(i)
    return roots