class_docstr: A ChainMap groups multiple dicts (or other mappings) together
  to create a single, updatable view.
  
  The underlying mappings are stored in a list.  That list is public and can
  be accessed / updated using the *maps* attribute.  There is no other state.
  
  Lookups search the underlying mappings successively until a key is found.
  In contrast, writes, updates, and deletions only operate on the first
  mapping.
docstr: New ChainMap with a new map followed by all previous maps. If no
  map is provided, an empty dict is used.
docstr_tok: ["New","ChainMap","with","a","new","map","followed","by","all","previous","maps",".","If","no","map","is","provided",",","an","empty","dict","is","used","."]
code: def new_child(self, m=None):  # like Django's Context.push()
      """
      New ChainMap with a new map followed by all previous maps. If no
      map is provided, an empty dict is used.
      """
      if m is None:
          m = {}
      return self.__class__(m, *self.maps)
  
imports: import sys
label_desc: Use image node_id 12 for calling the ChainMap obj's underlying member method code with example usage: obj.new_child(m) and returns: self