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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 encode_7or8bit(msg):
 """Set the Content-Transfer-Encoding header to 7bit or 8bit."""

    orig = msg.get_payload()
    if orig is None:
        # There's no payload.  For backwards compatibility we use 7bit
        msg['Content-Transfer-Encoding'] = '7bit'
        return
    # We play a trick to make this go fast.  If encoding/decode to ASCII
    # succeeds, we know the data must be 7bit, otherwise treat it as 8bit.
    try:
        if isinstance(orig, str):
            orig.encode('ascii')
        else:
            orig.decode('ascii')
    except UnicodeError:
        charset = msg.get_charset()
        output_cset = charset and charset.output_charset
        # iso-2022-* is non-ASCII but encodes to a 7-bit representation
        if output_cset and output_cset.lower().startswith('iso-2022-'):
            msg['Content-Transfer-Encoding'] = '7bit'
        else:
            msg['Content-Transfer-Encoding'] = '8bit'
    else:
        msg['Content-Transfer-Encoding'] = '7bit'
    if not isinstance(orig, str):
        msg.set_payload(orig.decode('ascii', 'surrogateescape'))