如何在Flask页面之间传递变量?

Suppose I have following case;

假设我有以下情况;

@app.route('/a', methods=['GET'])
def a():
  a = numpy.ones([10,10])
  ...
  return render_template(...) # this rendered page has a link to /b

@app.route('/b', methods=['GET'])
def b():
  print a
  ....
@a