class_docstr: A persistent bag/multiset type.
  
  Requires elements to be hashable, and allows duplicates, but has no
  ordering. Bags are hashable.
  
  Do not instantiate directly, instead use the factory functions :py:func:`b`
  or :py:func:`pbag` to create an instance.
  
  Some examples:
  
  >>> s = pbag([1, 2, 3, 1])
  >>> s2 = s.add(4)
  >>> s3 = s2.remove(1)
  >>> s
  pbag([1, 1, 2, 3])
  >>> s2
  pbag([1, 1, 2, 3, 4])
  >>> s3
  pbag([1, 2, 3, 4])
docstr: Update bag with all elements in iterable.
  
  >>> s = pbag([1])
  >>> s.update([1, 2])
  pbag([1, 1, 2])
docstr_tok: ["Update","bag","with","all","elements","in","iterable",".",">",">",">","s","=","pbag","(","[","1","]",")",">",">",">","s.update","(","[","1",",","2","]",")","pbag","(","[","1",",","1",",","2","]",")"]
code: def update(self, iterable):
      """
      Update bag with all elements in iterable.
  
      >>> s = pbag([1])
      >>> s.update([1, 2])
      pbag([1, 1, 2])
      """
      if iterable:
          return PBag(reduce(_add_to_counters, iterable, self._counts))
  
      return self
  
imports: from collections.abc import Container, Iterable, Sized, Hashable
  from functools import reduce
  from typing import Generic, TypeVar
  from pyrsistent._pmap import pmap
label_desc: Use image node_id 3 for calling the PBag obj's underlying member method code with example usage: obj.update(iterable) and returns: self, PBag