Make this simpler: Create a trading script that uses the following steps:

Define the currency pairs to trade as a list of symbols.
Define the initial balance as a dictionary with the currency pairs as keys and their corresponding prices as values. $1000 initial fund
Define the API keys for the trading platforms as a dictionary with the currency pairs as keys and the API keys as values. use coinbase
Define the trading strategy as a function that takes the previous day's closing prices for each currency pair as input. 
Use the strategy to generate trading signals for each currency pair.
Place limit orders to buy or sell the currency pairs based on the trading signals.
Monitor the order book and adjust or cancel orders as necessary.
Calculate the daily returns for each currency pair.
Calculate the overall return for the portfolio.
Return the portfolio balance at the end of each day.

Base this on a $1000 fund buying cryptocurrencies 