如何从Python-Behave步骤传递变量？

from behave import fixture, use_fixture

@fixture
def context_fixture(context):
    context.variable = None

def before_scenario(context, scenario):
    use_fixture(context_fixture, context)

from behave import given, when, then

@given('I have a variable "{variable}"')
def step_given_variable(context, variable):
    context.variable = variable

@when('I modify the variable')
def step_when_modify_variable(context):
    context.variable = 'modified'

@then('The variable should be "{expected}"')
def step_then_check_variable(context, expected):
    assert context.variable == expected