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: Combine elements from two PBags.
  
  >>> pbag([1, 2, 2]) + pbag([2, 3, 3])
  pbag([1, 2, 2, 2, 3, 3])
docstr_tok: ["Combine","elements","from","two","PBags",".",">",">",">","pbag","(","[","1",",","2",",","2","]",")","+","pbag","(","[","2",",","3",",","3","]",")","pbag","(","[","1",",","2",",","2",",","2",",","3",",","3","]",")"]
code: def __add__(self, other):
      """
      Combine elements from two PBags.
  
      >>> pbag([1, 2, 2]) + pbag([2, 3, 3])
      pbag([1, 2, 2, 2, 3, 3])
      """
      if not isinstance(other, PBag):
          return NotImplemented
      result = self._counts.evolver()
      for elem, other_count in other._counts.iteritems():
          result[elem] = self.count(elem) + other_count
      return PBag(result.persistent())
  
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 12 for calling the PBag obj's underlying member method code with example usage: obj.__add__(other) and returns: PBag, NotImplemented