add type annotation in rowcolranges

Author: dkarrasch

src/blockmap.jl

@@ -32,8 +32,8 @@ map in `maps`, according to its position in a virtual matrix representation of t
 block linear map obtained from `hvcat(rows, maps...)`.
 """
 function rowcolranges(maps, rows)
-    rowranges = ntuple(n->1:0, Val(length(rows)))
-    colranges = ntuple(n->1:0, Val(length(maps)))
+    rowranges::NTuple{length(rows),UnitRange{Int}} = ntuple(n->1:0, Val(length(rows)))
+    colranges::NTuple{length(maps),UnitRange{Int}} = ntuple(n->1:0, Val(length(maps)))
     mapind = 0
     rowstart = 1
     for (i, row) in enumerate(rows)