Let's start with a little C:

#include <stdio.h>

// This is a comment.
int main(int argc, char *argv[]) {
    printf("hello world\n");
    return 0;

And now some Python:

import argparse

class SomeClass:
    """ This is a docstring comment. """

    def __init__(self, arg=None):
        self.arg = arg or 21

    def method(self, arg=5):
        return arg * 42 + 12.5

# Lorem ipsum dolor sit amet.
def parse_args():
    parser = argparse.ArgumentParser()
    parser.add_argument('-v', '--version',
    return parser.parse_args()

Some HTML:

<!DOCTYPE html>
        <meta charset="utf-8">
        <title>Sample Page</title>
        <h1 class="heading">Test Page</h1>
        <p>Lorem ipsum dolor sit amet.</p>
        <!-- this is a comment -->

And let's finish with some Django template syntax:

{# This is a comment. #}

{% for post in posts %}
    <h1>{{ post.title }}</h1>
    <p>{{ post.content|striptags|truncatewords:50 }}</p>
{% endfor %}