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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def get_blockchain_fee_estimates(coin_symbol='btc', api_key=None):
 """ Returns high, medium, and low fee estimates for a given blockchain. """

    overview = get_blockchain_overview(coin_symbol=coin_symbol, api_key=api_key)
    return {
            'high_fee_per_kb': overview['high_fee_per_kb'],
            'medium_fee_per_kb': overview['medium_fee_per_kb'],
            'low_fee_per_kb': overview['low_fee_per_kb'],
            }