'Set up the initial "account" of the Position to be
zero for most items, with the exception of the initial
purchase/sale.
Then calculate the initial values and finally update the
market value of the transaction.'

def __init__(self, action, ticker, init_quantity, init_price, init_commission, bid, ask):

    self.action = action
    self.ticker = ticker
    self.quantity = init_quantity
    self.init_price = init_price
    self.init_commission = init_commission
    self.realised_pnl = 0
    self.unrealised_pnl = 0
    self.buys = 0
    self.sells = 0
    self.avg_bot = 0
    self.avg_sld = 0
    self.total_bot = 0
    self.total_sld = 0
    self.total_commission = init_commission
    self._calculate_initial_value()
    self.update_market_value(bid, ask)
