target multiple net47 and netstandard2.0

Let.cs.sln

@@ -1,33 +1,31 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
-# Visual Studio 2013
-VisualStudioVersion = 12.0.31101.0
+# Visual Studio 15
+VisualStudioVersion = 15.0.27004.2008
 MinimumVisualStudioVersion = 10.0.40219.1
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Let.cs", "Let.cs\Let.cs.csproj", "{10B3DC71-1A45-491D-BEC9-BEC1D6F254CB}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Let.cs", "src\Let.cs\Let.cs.csproj", "{B109B289-9646-4E19-AC73-157F49C71D6D}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Let.cs.Tests", "Let.cs.Tests\Let.cs.Tests.csproj", "{367994DD-EF59-4A06-9D70-FDA8B42131F7}"
-EndProject
-Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "nuget", "nuget", "{CDD4DABB-4598-49F1-ABE6-C38CE883B96F}"
-	ProjectSection(SolutionItems) = preProject
-		Let.cs\Let.cs.csproj.nuspec = Let.cs\Let.cs.csproj.nuspec
-	EndProjectSection
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Let.cs.Tests", "tests\Let.cs.Tests\Let.cs.Tests.csproj", "{EE5AAF0E-0CBC-4010-B987-ED071C318E52}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
 		Release|Any CPU = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
-		{10B3DC71-1A45-491D-BEC9-BEC1D6F254CB}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{10B3DC71-1A45-491D-BEC9-BEC1D6F254CB}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{10B3DC71-1A45-491D-BEC9-BEC1D6F254CB}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{10B3DC71-1A45-491D-BEC9-BEC1D6F254CB}.Release|Any CPU.Build.0 = Release|Any CPU
-		{367994DD-EF59-4A06-9D70-FDA8B42131F7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{367994DD-EF59-4A06-9D70-FDA8B42131F7}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{367994DD-EF59-4A06-9D70-FDA8B42131F7}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{367994DD-EF59-4A06-9D70-FDA8B42131F7}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B109B289-9646-4E19-AC73-157F49C71D6D}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B109B289-9646-4E19-AC73-157F49C71D6D}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B109B289-9646-4E19-AC73-157F49C71D6D}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B109B289-9646-4E19-AC73-157F49C71D6D}.Release|Any CPU.Build.0 = Release|Any CPU
+		{EE5AAF0E-0CBC-4010-B987-ED071C318E52}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{EE5AAF0E-0CBC-4010-B987-ED071C318E52}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{EE5AAF0E-0CBC-4010-B987-ED071C318E52}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{EE5AAF0E-0CBC-4010-B987-ED071C318E52}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {CEAB4523-3F35-4FE3-9168-50BAFDAC0AAB}
+	EndGlobalSection
 EndGlobal

src/Let.cs/Let.cs.csproj

@@ -0,0 +1,7 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFrameworks>net45;netstandard2.0</TargetFrameworks>
+  </PropertyGroup>
+
+</Project>