@Test
    public void canSetCustomExpressionStartChar() {
        CodeWriter writer = new CodeWriter();
        writer.pushState();
        writer.setExpressionStart('#');
        writer.write("Hi, #L", "1");
        writer.write("Hi, ##L");
        writer.write("Hi, $L");
        writer.write("Hi, $$L");
        writer.popState();
        writer.write("Hi, #L");
        writer.write("Hi, ##L");
        writer.write("Hi, $L", "2");
        writer.write("Hi, $$L");
        String result = writer.toString();

        assertThat(result,
                equalTo("Hi, 1\n"
                        + "Hi, #L\n"
                        + "Hi, $L\n"
                        + "Hi, $$L\n"
                        + "Hi, #L\n"
                        + "Hi, ##L\n"
                        + "Hi, 2\n"
                        + "Hi, $L\n"));
    }
\n"
                                + " * Foo \"foo!\"\n"
                                + " *\n"
                                + " * \"baz\"!\n"
                                + " * Yap!\n"
                                + " *     This is indented, in flow of parent.\n"
                                + " *     Yap!\n"
                                + " *     Yap?\n"
                                + " *     # Has a prefix\n"
                                + " *     # Yes\n"
                                + "
smithy-utils/src/test/java/software/amazon/smithy/utils/CodeWriterTest.java