refactor coroutine lowering and tasks

src/internal/task/task.go

@@ -0,0 +1,20 @@
+package task
+
+import (
+	"unsafe"
+)
+
+// Task is a state of goroutine for scheduling purposes.
+type Task struct {
+	// Next is a field which can be used to make a linked list of tasks.
+	Next *Task
+
+	// Ptr is a field which can be used for storing a pointer.
+	Ptr unsafe.Pointer
+
+	// Data is a field which can be used for storing state information.
+	Data uint
+
+	// state is the underlying running state of the task.
+	state state
+}