This is a built-in template used for filling the body of a Kotlin function each time it is generated by the program, e.g. when using the Create Function from Usage intention action. The template is editable. Along with Kotlin expressions and comments, you can also use the predefined variables that will be then expanded into the corresponding values.

Predefined variables will take the following values:
${RETURN_TYPE} |  | a return type of a created function
${FUNCTION_NAME} |  | name of the created function
${CLASS_NAME} |  | qualified name of the class where function is created
${SIMPLE_CLASS_NAME} |  | non-qualified name of the class where function is implemented