'Processes a list of splits by modifying any positions as needed.
Parameters
splits: list
A list of splits.  Each split is a tuple of (asset, ratio).
Returns
int: The leftover cash from fractional sahres after modifying each
position.'

def handle_splits(self, splits):

    total_leftover_cash = 0
    for (asset, ratio) in splits:
        if (asset in self.positions):
            position = self.positions[asset]
            leftover_cash = position.handle_split(asset, ratio)
            total_leftover_cash += leftover_cash
    return total_leftover_cash
