}
      // First, check whether var -> arg forms a cycle
      for (Type t = arg; t != null; t = mappings.get(TypeVariableKey.forLookup(t))) {
        if (var.equalsType(t)) {
          // cycle detected, remove the entire cycle from the mapping so that
          // each type variable resolves deterministically to itself.
          // Otherwise, an F -> T cycle will end up resolving both F and T

      }
      // First, check whether var -> arg forms a cycle
      for (Type t = arg; t != null; t = mappings.get(TypeVariableKey.forLookup(t))) {
        if (var.equalsType(t)) {
          // cycle detected, remove the entire cycle from the mapping so that
          // each type variable resolves deterministically to itself.
          // Otherwise, an F -> T cycle will end up resolving both F and T