如何在函数中访问从不同函数返回的变量？

global_var = None

def set_global_var(value):
    global global_var
    global_var = value

def get_global_var():
    return global_var

set_global_var(10)
print(get_global_var())  # 输出: 10

def set_value(value):
    return value

def process_value(value):
    return value * 2

value = set_value(10)
processed_value = process_value(value)
print(processed_value)  # 输出: 20

def get_values():
    return 10, 20

def process_values(value1, value2):
    return value1 + value2

value1, value2 = get_values()
result = process_values(value1, value2)
print(result)  # 输出: 30

class DataProcessor:
    def __init__(self):
        self.value = None

    def set_value(self, value):
        self.value = value

    def process_value(self):
        return self.value * 2

processor = DataProcessor()
processor.set_value(10)
result = processor.process_value()
print(result)  # 输出: 20