'All pyramiding trades close at the same time”翻译为“所有的金字塔交易同时关闭”。在代码示例中，可以使用以下代码来实现所有金字塔交易在同一时间关闭：

import backtrader as bt

class MyStrategy(bt.Strategy):
    params = (
        ('pyramiding', True),
        ('pyramiding_ratio', 0.5),
        ('pyramiding_spacing', 20),
    )

    def __init__(self):
        self.pyramiding_level = 0
        self.pyramiding_entry_price = None
        self.pyramiding_stop_loss_price = None

    def next(self):
        if self.pyramiding_level == 0:
            # Enter the first position
            self.buy()
            self.pyramiding_level += 1
            self.pyramiding_entry_price = self.data.close[0]
            self.pyramiding_stop_loss_price = self.pyramiding_entry_price * (1 - self.params.pyramiding_ratio)
        else:
            # Check if we need to add a new position
            if self.params.pyramiding and (self.pyramiding_level * self.params.pyramiding_spacing <= len(self)):
                if self.data.close[0] > self.pyramiding_entry_price * (1 + self.params.pyramiding_ratio):
                    # Enter a new position
                    self.buy()
                    self.pyramiding_level += 1
                    self.pyramiding_entry_price = self.data.close[0]
                    self.pyramiding_stop_loss_price = self.pyramiding_entry_price * (1 - self.params.pyramiding_ratio)

        # Check if we need to close all positions
        if self.pyramiding_level > 0 and self.pyramiding_stop_loss_price < self.data.close[0]:
            self.sell()
            self.pyramiding_level = 0

在上面的代码中，params中的pyramiding参数表示是否进行金字塔交易，pyramiding_ratio参数表示每个新仓位的大小相对于上一个仓位的比例，