class_docstr: A DataStoreStorage defines the interface of communication between the
  higher-level datastores and the actual storage system.
  
  Both the ContentAddressedStore and the TaskDataStore use these methods to
  read/write/list from the actual storage system. These methods are meant to
  be low-level; they are in a class to provide better abstraction but this
  class itself is not meant to be initialized.
docstr: Returns file size at the indicated 'path', or None if file can not be found.
  
  Parameters
  ----------
  path : string
      Path to the object
  
  Returns
  -------
  Optional
      int
docstr_tok: ["Returns","file","size","at","the","indicated","'path","'",",","or","None","if","file","can","not","be","found",".","Parameters","--","--","--","--","--","path",":","string","Path","to","the","object","Returns","--","--","--","-","Optional","int"]
code: def size_file(self, path):
      """
      Returns file size at the indicated 'path', or None if file can not be found.
  
      Parameters
      ----------
      path : string
          Path to the object
  
      Returns
      -------
      Optional
          int
      """
      raise NotImplementedError
  
imports: from collections import namedtuple
  import re
  from .exceptions import DataException
label_desc: Use image node_id 11 for calling the DataStoreStorage obj's underlying member method code with example usage: obj.size_file(path) without return types