public static IAsyncResult CheckMembership(
	OAuthTokens tokens,
	string ownerUsername,
	string listId,
	decimal userId,
	OptionalProperties options,
	TimeSpan timeout,
	Action<TwitterAsyncResponse<TwitterUser>> function
)

Public Shared Function CheckMembership ( _
	tokens As OAuthTokens, _
	ownerUsername As String, _
	listId As String, _
	userId As Decimal, _
	options As OptionalProperties, _
	timeout As TimeSpan, _
	function As Action(Of TwitterAsyncResponse(Of TwitterUser)) _
) As IAsyncResult