class_docstr: Model commissions by applying a fixed cost per dollar transacted.
  
  Parameters
  ----------
  cost : float, optional
      The flat amount of commissions paid per dollar of equities
      traded. Default is a commission of $0.0015 per dollar transacted.
class_docstr_tok: ["Model","commissions","by","applying","a","fixed","cost","per","dollar","transacted",".","Parameters","--","--","--","--","--","cost",":","float",",","optional","The","flat","amount","of","commissions","paid","per","dollar","of","equities","traded",".","Default","is","a","commission","of","$","0.0015","per","dollar","transacted","."]
docstr: Cost parameter is the cost of a trade per-dollar. 0.0015
  on $1 million means $1,500 commission (=1M * 0.0015)
code: def __init__(self, cost=DEFAULT_PER_DOLLAR_COST):
      """
      Cost parameter is the cost of a trade per-dollar. 0.0015
      on $1 million means $1,500 commission (=1M * 0.0015)
      """
      self.cost_per_dollar = float(cost)
  
imports: from abc import abstractmethod
  from collections import defaultdict
  from six import with_metaclass
  from toolz import merge
  from zipline.assets import Equity, Future
  from zipline.finance.constants import FUTURE_EXCHANGE_FEES_BY_SYMBOL
  from zipline.finance.shared import AllowedAssetMarker, FinancialModelMeta
  from zipline.utils.dummy import DummyMapping
label_desc: Use image node_id 1 to create a new PerDollar object from inherited base classes: EquityCommissionModel with example: obj = PerDollar(cost)