+ Closure of native validity
+ for context-sensitive extended computation.
+ </news>
+ <news date="2014 April 16.">
+ lazy equivalence on local environments
+ serves as irrelevant step in "big tree" computation
+ (anniversary milestone).
+ </news>
+ <news date="2014 January 20.">
+ Parametrized slicing for local environments
+ comprises both versions of this operation
+ (one from basic_1, the other used in basic_2 till now).