close the group (killing all fibers).
Return true if the current fiber is a member of the group
Initialize a new fiber group
Perform a task inside the current fiber as part of the group.
Perform a task inside the current fiber as part of the group.
Spawn a new fiber that will be a member of the group.
Conditionally spawn a new fiber, only if the fiber group is currently open.
Wait for all fibers in a group to exit.
report whether a fiber group is closed
3state execution results type
group of related fiber that may need to be killed together