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.
code: def get(self, key, default=None):
      return self[key] if key in self else default
  
imports: import sys
label_desc: Use image node_id 4 for calling the ChainMap obj's underlying member method code with example usage: obj.get(key, default) and returns: unknown