SMALL_BLOCK_SIZE

import std.algorithm.iteration : map;
import std.array : array;
import std.range : iota;
import std.stdio;

immutable filename = fileId("blocksegment").fullpath;
// writefln("filename=%s", filename);
auto file = File(filename, "w");
scope (exit) {
    file.close;
}
file.rawWrite(iota(SMALL_BLOCK_SIZE).map!(i => cast(ubyte) i).array);