Add elements to a vector.
A vector containing the values in x with the elements of
values appended after the specified element of x.
Becker RA, Chambers JM, Wilks AR (1988). The New S Language. Chapman and Hall/CRC, London. ISBN 053409192X.
append(1:5, 0:1, after = 3)
#> [1] 1 2 3 0 1 4 5