shared/idmap/idmapset_linux.go
func Extend(slice []IdmapEntry, element IdmapEntry) []IdmapEntry {
	n := len(slice)
	if n == cap(slice) {
		// Slice is full; must grow.
		// We double its size and add 1, so if the size is zero we still grow.
		newSlice := make([]IdmapEntry, len(slice), 2*len(slice)+1)
		copy(newSlice, slice)
		slice = newSlice
	}
	slice = slice[0 : n+1]
	slice[n] = element
	return slice
}
func Extend(slice []IdmapEntry, element IdmapEntry) []IdmapEntry {
	n := len(slice)
	if n == cap(slice) {
		// Slice is full; must grow.
		// We double its size and add 1, so if the size is zero we still grow.
		newSlice := make([]IdmapEntry, len(slice), 2*len(slice)+1)
		copy(newSlice, slice)
		slice = newSlice
	}
	slice = slice[0 : n+1]
	slice[n] = element
	return slice
}
/* taken from http://blog.golang.org/slices (which is under BSD licence) */