Creates a function type in a single-method object so its parameter types are checked bivariant-ly
under --strictFunctionTypes. Method-syntax members are bivariant; bare function-typed
properties are contravariant. Params is a tuple so multiple parameters can be defined.
Creates a function type in a single-method object so its parameter types are checked bivariant-ly under
--strictFunctionTypes. Method-syntax members are bivariant; bare function-typed properties are contravariant.Paramsis a tuple so multiple parameters can be defined.