-The built-in function copy copies slice elements from
+Two built-in functions assist in common slice operations.
+
+The function append appends zero or more values x
+to a slice s and returns the resulting slice. Each value must be
+assignable to the slice's element type.
+
+append(s []T, x ...T) []T ++ +
+If the capacity of s is not large enough to fit the additional
+values, append allocates a new, sufficiently large slice that fits
+both the existing slice elements and the additional values. Thus, the returned
+slice may refer to a different underlying array.
+
+s0 := []int{0, 0}
+s1 := append(s0, 2) // append a single element s1 == []int{0, 0, 2}
+s2 := append(s1, 3, 5, 7) // append multiple elements s2 == []int{0, 0, 2, 3, 5, 7}
+s3 := append(s2, s0...) // append a slice s3 == []int{0, 0, 2, 3, 5, 7, 0, 0}
+
+
+
+The function copy copies slice elements from
a source src to a destination dst and returns the
number of elements copied. Source and destination may overlap.
Both arguments must have identical element type T and must be