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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 get_atomtrailer_list(r):
 """Capture only the leading dotted name list. A full sequence typically includes function calls and parameters. pkga.pkgb.pkgc.one_call(arg1, arg2, arg3=4) """

    dot_set = set()
    for n in r.find_all(("atomtrailers",)):
        name_list = []
        for x in n.value:
            if x.type != "name":
                break
            name_list.append(x.value)
        if name_list:
            dot_set.add(tuple(name_list))
    return sorted(dot_set)