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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 re_tab(s):
 """Return a tabbed string from an expanded one."""

    l = []
    p = 0
    for i in range(8, len(s), 8):
        if s[i - 2:i] == "  ":
            # collapse two or more spaces into a tab
            l.append(s[p:i].rstrip() + "\t")
            p = i

    if p == 0:
        return s
    else:
        l.append(s[p:])
        return "".join(l)