def __init__(self,
                 cost=DEFAULT_PER_SHARE_COST,
                 min_trade_cost=DEFAULT_MINIMUM_COST_PER_TRADE):
        self.cost = float(cost)
        self.min_trade_cost = None if min_trade_cost is None\
            else float(min_trade_cost)
Cost parameter is the cost of a trade per-share. $0.03
dataset/ETHPy150Open quantopian/zipline/zipline/finance/commission.py/PerShare.__init__