def lookup_in_scope(name, scope)
      n = scope.size
      while n >= 0
        tn = (scope[0,n] + [name]).join(':')
        task = @tasks[tn]
        return task if task
        n -= 1
      end
      nil
    end
def lookup_in_scope(name, scope)
      n = scope.size
      while n >= 0
        tn = (scope[0,n] + [name]).join(':')
        task = @tasks[tn]
        return task if task
        n -= 1
      end
      nil
    end
Lookup the task name