public static StringBuilder AppendJoin<T>(
	this StringBuilder sb,
	string separator,
	IEnumerable<T> values,
	Action<StringBuilder, T, int> valueAppender
)

[<ExtensionAttribute>]
static member AppendJoin : 
        sb : StringBuilder * 
        separator : string * 
        values : IEnumerable<'T> * 
        valueAppender : Action<StringBuilder, 'T, int> -> StringBuilder