This function creates a
"markedBlock" object, which is
a description of a block of binary data. This can be used
as part of a description of a binary format.
A function that returns a
"markedBlock" object describes a block of binary data that consists
of a “marker” block containing information on further blocks.
marker block is read first, then this block is passed
switch function. The
can look at the contents of the
marker block and decide
what sort of block should be read next. The result of the
switch function is read from the end of the
marker block and the result of the
function can be any type
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