class Stock:
    def __init__(self, symbol):
        self.symbol = symbol
        self.price_history = []

    @property
    def price(self):
        return self.price_history[-1] if self.price_history else None

    def update(self, timestamp, price):
        if price < 0:
            raise ValueError("price should not be negative")
        self.price_history.append(price)

    def is_increasing_trend(self):
        return self.price_history[-3] < self.price_history[-2] < self.price_history[-1]

import bisect
import collections

PriceEvent = collections.namedtuple("PriceEvent", ["timestamp", "price"])


class Stock:
    def __init__(self, symbol):
        self.symbol = symbol
        self.price_history = []

    @property
    def price(self):
        return self.price_history[-1].price if self.price_history else None

    def update(self, timestamp, price):
        if price < 0:
            raise ValueError("price should not be negative")
        bisect.insort_left(self.price_history, PriceEvent(timestamp, price))

    def is_increasing_trend(self):
        return self.price_history[-3].price < self.price_history[-2].price < self.price_history[-1].price

Add a named tuple PriceEvent sub class and update methods accordingly.
Add a named tuple PriceEvent sub class and update methods accordingly.

+ import bisect
+ import collections
+ 
+ PriceEvent = collections.namedtuple("PriceEvent", ["timestamp", "price"])
+ 
+ 
  class Stock:
      def __init__(self, symbol):
          self.symbol = symbol
          self.price_history = []
  
      @property
      def price(self):
-         return self.price_history[-1] if self.price_history else None
+         return self.price_history[-1].price if self.price_history else None
  
      def update(self, timestamp, price):
          if price < 0:
              raise ValueError("price should not be negative")
-         self.price_history.append(price)
+         bisect.insort_left(self.price_history, PriceEvent(timestamp, price))
  
      def is_increasing_trend(self):
-         return self.price_history[-3] < self.price_history[-2] < self.price_history[-1]
+         return self.price_history[-3].price < self.price_history[-2].price < self.price_history[-1].price
  
Add a named tuple PriceEvent sub class and update methods accordingly.
## Code Before:
class Stock:
    def __init__(self, symbol):
        self.symbol = symbol
        self.price_history = []

    @property
    def price(self):
        return self.price_history[-1] if self.price_history else None

    def update(self, timestamp, price):
        if price < 0:
            raise ValueError("price should not be negative")
        self.price_history.append(price)

    def is_increasing_trend(self):
        return self.price_history[-3] < self.price_history[-2] < self.price_history[-1]

## Instruction:
Add a named tuple PriceEvent sub class and update methods accordingly.
## Code After:
import bisect
import collections

PriceEvent = collections.namedtuple("PriceEvent", ["timestamp", "price"])


class Stock:
    def __init__(self, symbol):
        self.symbol = symbol
        self.price_history = []

    @property
    def price(self):
        return self.price_history[-1].price if self.price_history else None

    def update(self, timestamp, price):
        if price < 0:
            raise ValueError("price should not be negative")
        bisect.insort_left(self.price_history, PriceEvent(timestamp, price))

    def is_increasing_trend(self):
        return self.price_history[-3].price < self.price_history[-2].price < self.price_history[-1].price
