GString.opApply

auto t1 = typeof(this)("Test R̆ȧm͆b̪õ");
StringT nakedString;
StringT nakedExpected = "Test Rambo";
size_t isum = 0;
foreach (i, g; t1) {
  isum += i;
  nakedString ~= g[0];
}
assert(isum == 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9);
assert(nakedString == nakedExpected);