made Seq module internal and moved to own file

src/Hedgehog/Hedgehog.fsproj

@@ -28,6 +28,7 @@ https://github.com/hedgehogqa/fsharp-hedgehog/blob/master/doc/index.md
     <Compile Include="AutoOpen.fs" />
     <Compile Include="Numeric.fs" />
     <Compile Include="Seed.fs" />
+    <Compile Include="Seq.fs" />
     <Compile Include="Tree.fs" />
     <Compile Include="OptionTree.fs" />
     <Compile Include="Range.fs" />

src/Hedgehog/Seq.fs

@@ -0,0 +1,17 @@
+[<RequireQualifiedAccess>]
+module internal Seq
+
+let inline cons (x : 'a) (xs : seq<'a>) : seq<'a> =
+    seq {
+        yield x
+        yield! xs
+    }
+
+let inline consNub (x : 'a) (ys0 : seq<'a>) : seq<'a> =
+    match Seq.tryHead ys0 with
+    | None -> Seq.singleton x
+    | Some y ->
+        if x = y then
+            ys0
+        else
+            cons x ys0

src/Hedgehog/Shrink.fs

@@ -1,21 +1,5 @@
 namespace Hedgehog
 
-module Seq =
-    let cons (x : 'a) (xs : seq<'a>) : seq<'a> =
-        seq {
-            yield x
-            yield! xs
-        }
-
-    let consNub (x : 'a) (ys0 : seq<'a>) : seq<'a> =
-        match Seq.tryHead ys0 with
-        | None -> Seq.singleton x
-        | Some y ->
-            if x = y then
-                ys0
-            else
-                cons x ys0
-
 
 module Shrink =
     /// Produce all permutations of removing 'k' elements from a list.