def get_block_hash(block_height, coin_symbol='btc', api_key=None):
    '''
    Takes a block_height and returns the block_hash
    '''
    return get_block_overview(block_representation=block_height,
            coin_symbol=coin_symbol, txn_limit=1, api_key=api_key)['hash']
Takes a block_height and returns the block_hash