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: Clear maps[0], leaving maps[1:] intact.
docstr_tok: ["Clear","maps","[","0","]",",","leaving","maps","[","1",":","]","intact","."]
code: def clear(self):
      "Clear maps[0], leaving maps[1:] intact."
      self.maps[0].clear()
  
imports: import sys
label_desc: Use image node_id 18 for calling the ChainMap obj's underlying member method code with example usage: obj.clear() without return types