unpack template, string
Takes a string (string) representing a data structure
and expands it into a list value, returning the list value. (unpack
does the reverse of pack.) In a scalar
context, it can be used to unpack a single value. The
template has much the same format as in the pack
function - it specifies the order and
type of the values to be unpacked. (See pack for a more detailed description of
template.)