From: Rob Pike a can be discovered
using the built-in function len(a), which is a
compile-time constant. The elements can be indexed by integer
indices 0 through the len(a)-1 (§Indexes).
+Array types are always one-dimensional but may be composed to form
+multi-dimensional types.
[32]byte
[2*N] struct { x, y int32 }
[1000]*float64
+[3][5]int
+[2][2][2]float64 // same as [2]([2]([2]float64))
+Like arrays, slices are always one-dimensional but may be composed to construct
+higher-dimensional objects.
+With arrays of arrays, the inner arrays are, by construction, always the same length;
+however with slices of slices (or arrays of slices), the lengths may vary dynamically.
+Moreover, the inner slices must be allocated individually (with make).
+