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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 markup_join(seq):
 """Concatenation that escapes if necessary and converts to unicode."""

    buf = []
    iterator = imap(soft_unicode, seq)
    for arg in iterator:
        buf.append(arg)
        if hasattr(arg, '__html__'):
            return Markup(u'').join(chain(buf, iterator))
    return concat(buf)