public static EnumDeclarationSyntax AddModifiers(this EnumDeclarationSyntax @this,
     MODIFIER @modifier)
 {
     return @this.AddModifiers(
         @modifier.GetSyntaxTokens().ToArray());
 }
 public static ParameterSyntax WithRef(this ParameterSyntax syntax, bool isRef)
 {
     if (isRef) return syntax.AddModifiers(SyntaxFactory.Token(SyntaxKind.RefKeyword));
     else return syntax.WithModifiers(SyntaxFactory.TokenList());
 }
 public static MethodDeclarationSyntax WithStaticKeyword(this MethodDeclarationSyntax syntax)
 {
     return syntax.AddModifiers (SF.Token (SyntaxKind.StaticKeyword));
 }
 public static MethodDeclarationSyntax WithStatic(this MethodDeclarationSyntax syntax, bool isStatic)
 {
     if (isStatic) return syntax.AddModifiers(SyntaxFactory.Token(SyntaxKind.StaticKeyword));
     else return syntax.WithModifiers(SyntaxFactory.TokenList());
 }
 public static ConstructorDeclarationSyntax WithStaticKeyword(this ConstructorDeclarationSyntax syntax)
 {
     return syntax.AddModifiers (SF.Token (SyntaxKind.StaticKeyword));
 }