diff --git a/src/mol-comp/util.ts b/src/mol-comp/util.ts
index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..29e347d32897623d0d1706e0e557c3e2f2524e3d 100644
--- a/src/mol-comp/util.ts
+++ b/src/mol-comp/util.ts
@@ -0,0 +1,53 @@
+
+
+
+type ExecutionContext = { getRuntimeCtx(c: Computation<any>): RuntimeContext, subscribe(o: (p: string, compId: number) => void): void }
+
+type RuntimeContext = { yield(name: string): Promise<void> | void, createChildContext(): RuntimeContext }
+
+type Computation<T> = { (ctx?: RuntimeContext): Promise<T>, _id: number }
+
+function create<T>(c: (ctx: RuntimeContext) => Promise<T>): Computation<T> { return 0 as any; }
+
+type MultistepFn<P, T> = (params: P, step: (s: number) => Promise<void> | void, ctx: RuntimeContext) => Promise<T>
+type ComputationProvider<P, T> = (params: P) => Computation<T>
+function MultistepComputation<P, T>(name: string, steps: string[], f: MultistepFn<P, T>): ComputationProvider<P, T> {
+    return params => create(async ctx => f(params, n => ctx.yield(steps[n]), ctx));
+}
+
+
+// if total count is specified, could automatically provide percentage
+type UniformlyChunkedFn<S> = (chunkSize: number, state: S, totalCount?: number) => number
+type UniformlyChunkedProvider<S> = (ctx: RuntimeContext, state: S) => Promise<S>
+function UniformlyChunked<S>(label: string, initialChunk: number, f: UniformlyChunkedFn<S>): UniformlyChunkedProvider<S> {
+    // TODO: track average time required for single element and then determine chunk size based on that.
+    return 0 as any;
+}
+
+const uniformPart = UniformlyChunked('Reading lines', 1000000, (size, state: { str: string, position: number, lines: string[] }) => {
+    state.position += size;
+    state.lines.push('');
+    return 0 /* number of lines read */;
+});
+
+function readLines(str: string): Computation<string[]> {
+    return create(async ctx => {
+        const state = { str, position: 0, lines: [] };
+        await uniformPart(ctx, state);
+        return state.lines;
+    });
+}
+
+const prependHiToLines = MultistepComputation('Hi prepend', ['Parse input', 'Prepend Hi'], async (p: string, step, ctx) => {
+    await step(0);
+    const lines = await readLines(p)(ctx);
+    await step(1);
+    const ret = lines.map(l => 'Hi ' + l);
+    return ret;
+});
+
+
+(async function() {
+    const r = await prependHiToLines('1\n2')();
+    console.log(r)
+}())