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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 read_sections(sections_file, exclude_ungrouped=False, prt=sys.stdout):
 """Get sections and GO grouping hdrgos from file, if sections exist."""

    if sections_file is None:
        return None
    assert isinstance(sections_file, str), "BAD SECTIONS FILENAME({S})".format(
        S=sections_file)
    if os.path.exists(sections_file):
        return ReadGoids().read_sections(sections_file, False, exclude_ungrouped)
    # Is 'sections_file' a module string?
    if '/' not in sections_file and r'\\' not in sections_file and \
            pkgutil.find_loader(sections_file) is not None:
        mod = importlib.import_module(sections_file)
        var = getattr(mod, 'SECTIONS', None)
        if var is not None:
            dat = SummarySec2dHdrGos().summarize_sec2hdrgos(var)
            print(Grouper.fmtsum.format(
                GO_DESC='hdr', SECs=len(dat['S']), GOs=len(dat['G']),
                UNGRP="N/A", undesc="unused", ACTION="IMPORTED: ", FILE=sections_file))
            return var
        raise RuntimeError("NO 'SECTIONS' VARIABLE FOUND IN MODULE({M})".format(M=sections_file))
    if prt:
        prt.write("CANNOT READ: {SEC}\n".format(SEC=sections_file))