w many bytes are left for the first
line of <tt>B</tt> and '<tt>m</tt>' returns the number of bytes
left in the last line of <tt>A</tt>.
</p>

<p class="note">
Note: Besides breaking text into lines, this function makes sure the line
breaks don't fall in the middle of an escaped character combination. Also,
this function only breaks lines that are bigger than <tt>length</tt> bytes.
</p>

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<p class="name" id="unb64">
A, B = mime.<