Position = namedtuple('Position', 'x y')
Health = namedtuple('Health', 'value')
Movable = namedtuple('Movable', '')

entity.add(Position, 3, 7)
entity.add(Health, 100)
entity.add(Movable)

entity.replace(Position, 10, 100)
entity.replace(Health, entity.get(Health).value - 1)

entity.remove(Position)

has_pos = entity.has(Position)
movable = entity.has(Movable)

context = Context()
entity = context.create_entity()
entity.add(Movable)

entities = context.entities
for e in entities:
    # do something

context.get_group(Matcher(Position)).entities

def move(entity, new_comp):
    # do something

context.get_group(Matcher(Position)).on_entity_added += move

group = context.get_group(Matcher(Position))
collector = Collector()
collector.add(group, GroupEvent.added)

# later

for e in collector.collected_entities:
   # do something with all the entities
   # that have been collected to this point of time

collector.clear_collected_entities()

# stop observing
collector.deactivate()

Person = namedtuple('Person', 'name age')
group = context.get_group(Matcher(Person))

# get a set of 42-year-old Person
index = EntityIndex(Person, group, 'age')
context.add_entity_index(index)
entities = context.get_entity_index(Person).get_entities(42)

# get the Person named "John"
primary_index = PrimaryEntityIndex(Person, group, 'name')
context.add_entity_index(primary_index)
entity = context.get_entity_index(Person).get_entity('John')

class RenderDisplay(ExecuteProcessor):

    def execute(self):
        pygame.display.update()


# Initialize, Cleanup and TearDown are also available.


class Move(ReactiveProcessor):

    def __init__(self, context):
        super().__init__(context)
        self._context = context

    def get_trigger(self):
        return {Matcher(Position): GroupEvent.ADDED}

    def filter(self, entity):
        return entity.has(Position, Movable)

    def react(self, entities):
        for entity in entities:
            # use entity.get(Position).x & entity.get(Position).y

context = Context()

processors = Processors()
processors.add(StartGame(context))
processors.add(InputProcessors(context))
processors.add(RenderDisplay())
processors.add(DestroyEntity(context))

processors.initialize()
processors.activate_reactive_processors()

# main loop
running = True
while running:
    processors.execute()
    processors.cleanup()

    if EmitInput.quit:
        break

processors.clear_reactive_processors()
processors.tear_down()

quit()