feature := take(&required)
			if exceptionSet[feature] {
				// An "unfortunate" case: the feature was once
				// included in the API (e.g. go1.txt), but was
				// subsequently removed. These are already
				// acknowledged by being in the file
				// "api/except.txt". No need to print them out
				// here.
			} else if portRemoved(feature) {
				// okay.
			} else if featureSet[featureWithoutContext(feature)] {
				// okay.

     * do, when columnKeys is empty but rowKeys isn't, rowKeyList() can contain
     * elements but rowKeySet() will be empty and containsRow() won't
     * acknowledge them.
     */
    rowKeyToIndex = Maps.indexMap(rowList);
    columnKeyToIndex = Maps.indexMap(columnList);

    @SuppressWarnings("unchecked")
    @Nullable

    Further, Affirmer disclaims responsibility for obtaining any necessary
    consents, permissions or other rights required for any use of the
    Work.
 d. Affirmer understands and acknowledges that Creative Commons is not a
    party to this document and has no duty or obligation with respect to
    this CC0 or use of the Work.

================================================================