Z supports the notion of sequences where a sequence is like an array. For example, for a sequence S, you can refer to its elements as S[1], S[2], and so on. It also allows you to determine the number of elements in a sequence using the # operator. That is, if a sequence S is [a,

b, c, d] then #S is 4. You can add an element to the end of a sequence S by writing S

+

a, and to the beginning of the sequence by writing a + S. Using these constructs, write a Z specification of the LIST that is specified algebraically in Figure 10.7.