<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def decide(self, package):
 # type: (Package) -> None """ Adds an assignment of package as a decision and increments the decision level. """

        # When we make a new decision after backtracking, count an additional
        # attempted solution. If we backtrack multiple times in a row, though, we
        # only want to count one, since we haven't actually started attempting a
        # new solution.
        if self._backtracking:
            self._attempted_solutions += 1

        self._backtracking = False
        self._decisions[package.name] = package

        self._assign(
            Assignment.decision(package, self.decision_level, len(self._assignments))
        )