[self block:^(void) {
  doStuff();
} completionHandler:^(void) {
  doStuff();

  [self block:^(void) {
    doStuff();
  } completionHandler:^(void) {
    doStuff();
  }];
}];

[self setupTextFieldSignals:@[
  self.documentWidthField,
  self.documentHeightField,
] solver:^(NSTextField *textField) {
  return [self.representedObject solveEquationForTextField:textField];
}];