Type defines which operations can be performed on data, and how that data, or values, are stored for that type. There are common types, such as integer and string, composite types, and custom types. Also see primitive type and container type. The type keyword can be used with curly braces to define an expected type. Function declarations and numeric ranges are currently supported as declarations. For example, the Subscribe() function for the subscribable interface uses the type keyword to define that its Callback parameter must be a function with a void return type.
Verse
Subscribe<public>(Callback:type {__(:t):void})<transacts>:cancelable