drscheme:language:extend-language-interface in DrScheme Tools Functions

• (drscheme:language:extend-language-interface interface default-implementation) -> void?
     interface : interface?
     default-implementation : ((implementation?/c drscheme:language:language<%>) . ->d . (lambda (%) (subclass?/c %)))

  This function can only be called in phase 1.

  Each language added passed to drscheme:language-configuration:add-language must implement interface.

  The default-implementation is a mixin that provides a default implementation of interface. Languages that are unaware of the specifics of extension use default-implementation via drscheme:language:get-default-mixin.