Factory methods for Sequences 
What it is  What it does 
S.empty  The empty sequence. 
S(x, y, z)  A sequence consisting of elements x, y, z. 
S.concat(xs, ys, zs)
 The sequence obtained by concatenating the elements
of xs, ys, zs. 
S.fill(n){e}
 A sequence of length n where each element is computed by
expression e. 
S.fill(m, n){e}
 A sequence of sequences of dimension m×n
where each element is computed by expression e.
(exists also in higher dimensions). 
S.tabulate(n){f}
 A sequence of length n where the element at each index
i is computed by f(i). 
S.tabulate(m, n){f}
 A sequence of sequences of dimension m×n
where the element at each index
(i, j) is computed by f(i, j).
(exists also in higher dimensions). 
S.range(start, end)
 The sequence of integers start ... end1. 
S.range(start, end, step)
 The sequence of integers starting with start and
progressing by step increments up to, and excluding, the
end value. 
S.iterate(x, n)(f)
 The sequence of length n with elements
x, f(x), f(f(x)), ....
