Change indentation level to 2 (from 4) and rename MCE_DEF_SETTINGS to
DEF_MCE_SETTINGS to match the "default constant" naming convention elsewhere
in the code.
indexes:
# AUTOGENERATED
# This index.yaml is automatically updated whenever the dev_appserver
# detects that a new type of query is run. If you want to manage the
# index.yaml file manually, remove the above marker line (the line
# saying "# AUTOGENERATED"). If you want to manage some indexes
# manually, move them above the marker line. The index.yaml file is
# automatically uploaded to the admin console when you next deploy
# your application using appcfg.py.