class Jekyll::Configuration

Returns a Configuration filled with defaults.

user_config - a Hash or Configuration of overrides.

It takes the input, fills in the defaults where values do not exist.
Static: Produce a Configuration ready for use in a Site.

def from(user_config)
  Utils.deep_merge_hashes(DEFAULTS, Configuration[user_config].stringify_keys)
    .add_default_collections.add_default_excludes
end