isSymbolASCII

assert(isSymbolASCII("alpha", 0, 5));
assert(isSymbolASCII(" alpha ", 1, 6));
assert(!isSymbolASCII("driver", 0, 5));
assert(!isSymbolASCII("a_word", 0, 1));
assert(!isSymbolASCII("first_a_word", 6, 7));