fib.cs

        [Command("fib")]
        [Alias("fibonnaci")]
        [Syntax("fib <n>")]
        [RequireRole("staff")]
        public async Task Fib(int n)
        {
            if (n <= 0) { await ReplyAsync("No."); return; }

            if (n == 1) { await ReplyAsync("0");  return; }
            if (n == 2) { await ReplyAsync("1"); return; }

            var typing = Context.Channel.EnterTypingState();

            var startTime = HighResolutionDateTime.UtcNow;
            (var a, var b) = ((BigInteger)1, (BigInteger)1); for (var i = 0; i < n - 3; i++) 
            {
                b = a + b; a = b - a; 
                if ((HighResolutionDateTime.UtcNow - startTime).TotalMilliseconds > 1000 * 60 * 5)
                {
                    typing.Dispose();
                    await this.ReactError();
                    await ReplyAsync("Computation took more than 2 minutes, cancelled. Sorry!");
                    return;
                }
            }
            var took = (HighResolutionDateTime.UtcNow - startTime).TotalMilliseconds;
            await this.ReactOk();

            var s = b.ToString();
            var parts = await s.SplitWithLength(1950);

            if (parts.Count > 5)
            {
                await ReplyAsync($"__Fibonacci Results__\nn = {n}\nTook {took} ms.\nfib(n) has {s.Length} digits.\n" +
                    $"Did not post due to requiring {parts.Count} messages.");
                typing.Dispose();
                return;
            }

            foreach (var p in parts)
            {
                await ReplyAsync("```\n" + p + "\n```");
            }

            await ReplyAsync($"__Fibonacci Results__\nn = {n}\nTook {took} ms.\nfib(n) has {s.Length} digits.");
            typing.Dispose();
        }