collections

merge(dest, source)

Merges source into dest; entries in source take precedence over dest.

This routine may modify dest and should be assigned to dest, in case dest was None to begin with, e.g.:

dest = merge(dest, source)

In the result, elements from lists from source will appear before elements of lists from dest. Likewise, when iterating over keys or items in merged OrderedDict objects, keys from source will appear before keys from dest.

Config file authors can optionally end any attribute in a dict with :: instead of :, and the key will override that of the parent instead of merging.