LowType enhances Ruby by allowing type expressions in method arguments. Instead of requiring a specific value, you can now specify a type as a default. For example, in a method like `say_hello(greeting: String)`, it raises an exception at runtime if the argument isn't a String. You can also provide a default value using the pipe symbol (|), such as `greeting = String | 'Hello'`, which allows for clear type definitions and defaults. The library also supports complex types with enumerables. You can define an array of types using the syntax `Array[String]` or a hash with `Hash[String => Integer]`. Return types can be specified using the syntax `-> { T }`, ensuring that methods return the expected type. There’s flexibility for multi-line return types as well. For instance, you can define a method that returns instances of multiple classes neatly with the syntax `-> { ::Long::Name::Space::CustomClassOne | ::Long::Name::Space::CustomClassTwo }`. Instance variables can be typed using methods like `type_reader`, `type_writer`, and `type_accessor`. These methods function similarly to Ruby's built-in attribute methods but include type checking. The `type()` method allows local variables to be defined with a specific type during runtime, adding another layer of type safety. The settings for LowType can be configured, including toggling type checking on or off, which can be useful in different environments. LowType evaluates type expressions at class load for efficiency, while runtime evaluations occur for method parameters and local variables. This design aims to maintain performance while adding robust type safety features to Ruby.