Error in Iteration example in A Tour of the Dart Libraries - dart

Question

Problem
How can I implement the example of Iteration in A Tour of the Dart Libraries?
I understood that it is a code that must be supplemented, but how do I supplement it?
A Tour of the Dart Libraries
class Process {
// Represents a process...
}
class ProcessIterator implements Iterator<Process> {
#override
Process get current => ...
#override
bool moveNext() => ...
}
// A mythical class that lets you iterate through all
// processes. Extends a subclass of [Iterable].
class Processes extends IterableBase<Process> {
#override
final Iterator<Process> iterator = ProcessIterator();
}
void main() {
// Iterable objects can be used with for-in.
for (var process in Processes()) {
// Do something with the process.
}
}
Development Environment
Dart 2
DartPad
Tried → Error
I read and executed the document on my own, but the following error occurred.
class ProcessIterator implements Iterator<Process> {
#override
Process get current => new Process();
#override
bool moveNext() => false;
}
-> Error: 'IterableBase' expects 0 type arguments.
Best regards,

Answer 1

Two things.
1) Process is not available on the web, so your DartPad example won't work.
2) IterableBase is in dart:collection. Don't forget to import that.
This code seems to work for me:
import 'dart:collection';
class ProcessIterator implements Iterator<int> {
#override
int get current => 0;
#override
bool moveNext() => false;
}
// A mythical class that lets you iterate through all
// processes. Extends a subclass of [Iterable].
class Processes extends IterableBase<int> {
#override
final Iterator<int> iterator = ProcessIterator();
}
main() {
for (var thing in Processes()) {
print(thing);
}
}
Keep in mind, it's often MUCH easier to use sync* for custom iterators.
Iterable<int> _myProcesses() sync* {
yield 1;
yield 2;
yield 3;
}
main() {
for (var thing in _myProcesses()) {
print(thing);
}
}

Answer 2

Refer to #Kevin 's answer and rewrite the code below.
Code
import 'dart:collection';
class Process {
var foo = 'foo';
}
class ProcessIterator implements Iterator<Process> {
int i = 0;
#override
Process get current => new Process();
#override
bool moveNext() {
if(i++ < 5) {
return true;
} else {
return false;
}
}
}
// A mythical class that lets you iterate through all
// processes. Extends a subclass of [Iterable].
class Processes extends IterableBase<Process> {
#override
final Iterator<Process> iterator = ProcessIterator();
}
void main() {
// Iterable objects can be used with for-in.
for (var process in Processes()) {
print(process.foo);
}
}
Console
foo
foo
foo
foo
foo