for (Entry<TypeVariableKey, ? extends Type> mapping : mappings.entrySet()) {
        TypeVariableKey variable = mapping.getKey();
        Type type = mapping.getValue();
        checkArgument(!variable.equalsType(type), "Type variable %s bound to itself", variable);
        builder.put(variable, type);
      }
      return new TypeTable(builder.buildOrThrow());
    }

    final Type resolve(TypeVariable<?> var) {