class_docstr: A position held by an algorithm.
  
  Attributes
  ----------
  asset : zipline.assets.Asset
      The held asset.
  amount : int
      Number of shares held. Short positions are represented with negative
      values.
  cost_basis : float
      Average price at which currently-held shares were acquired.
  last_sale_price : float
      Most recent price for the position.
  last_sale_date : pd.Timestamp
      Datetime at which ``last_sale_price`` was last updated.
class_docstr_tok: ["A","position","held","by","an","algorithm",".","Attributes","--","--","--","--","--","asset",":","zipline.assets.Asset","The","held","asset",".","amount",":","int","Number","of","shares","held",".","Short","positions","are","represented","with","negative","values",".","cost_basis",":","float","Average","price","at","which","currently-held","shares","were","acquired",".","last_sale_price",":","float","Most","recent","price","for","the","position",".","last_sale_date",":","pd.Timestamp","Datetime","at","which","``","last_sale_price","``","was","last","updated","."]
code: def sid(self):
      # for backwards compatibility
      return self.asset
  
imports: from warnings import warn
  import pandas
  from .assets import Asset
  from .utils.enum import enum
  from ._protocol import BarData, InnerPosition
label_desc: Use image node_id 4 for calling the Position obj's underlying member method code with example usage: obj.sid() and returns: self