class_docstr: Keeps and updates the size and price of a position. The object has no
  relationship to any asset. It only keeps size and price.
  
  Member Attributes:
    - size (int): current size of the position
    - price (float): current price of the position
  
  The Position instances can be tested using len(position) to see if size
  is not null
class_docstr_tok: ["Keeps","and","updates","the","size","and","price","of","a","position",".","The","object","has","no","relationship","to","any","asset",".","It","only","keeps","size","and","price",".","Member","Attributes",":","-","size","(","int",")",":","current","size","of","the","position","-","price","(","float",")",":","current","price","of","the","position","The","Position","instances","can","be","tested","using","len","(","position",")","to","see","if","size","is","not","null"]
code: def __len__(self):
      return abs(self.size)
  
file_path: backtrader/backtrader/position.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from copy import copy
label_desc: Use image node_id 5 for calling the Position obj's underlying member method code with example usage: obj.__len__() and returns: abs