Given a stream of stock data, create a data structure that can efficiently handle the following functions:

• execute_trade(ticker, volume) - store the trade that has occurred
• most_traded(k) - return the $k$ most traded stocks by volume. The return format should be a list of strings with each string being formatted as: <TICKER> <VOLUME>

Example:

st = StockTracker()
st.execute_trade('TSLA', 1000)
st.execute_trade('NFLX', 700)
st.execute_trade('TSLA', 200)
st.execute_trade('META', 1400)
st.most_traded(2)
# This should return the following:
# META 1400
# TSLA 1200

Complete the following class for your solution

from typing import List

class StockTracker:
    def __init__(self) -> None:
        pass

    def execute_trade(self, ticker: str, volume: int) -> None:
        pass

    def most_traded(self, k: int) -> List[str]:
        pass