# fn:last - XPath XQuery Reference

Returns the context size from the dynamic context.deterministiccontext-dependentfocus-dependentspecial-streaming-rulesReturns the context size from the dynamic context. (See .)(1 to 20)[fn:last() - 1]19A dynamic error is raised  if
            the context size is absent.Under most circumstances, the context size is absent only if the context item is absent. However, XSLT 3.0 with
         streaming defines situations in which the context item and context position are known, but the context size is unknown.