Package for a subclass of Range, RangeExtd, containing RangeExtd::Infinity and RangeExtd::Nowhere. RangeExtd defines ranges that enable an exclusion of the begin boundary, in addition to the end boundary as in the built-in Range, and accepts open-ended ranges to infinity for either (or both) positive/negative direction. The open-ended boundaries are represented by two constant objects, POSITIVE and NEGATIVE of RangeExtd::Infinity, and they are a generalised Infinity of Float::INFINITY to any Comparable objects, which are in practice similar to built-in beginless/endless Ranges.