Returns an HTML snippet for an environment variable.

    Args:
        key: A string representing an environment variable name.

    Returns:
        String HTML representing the value and variable.

def html_for_env_var(key):
    """Returns an HTML snippet for an environment variable.

    Args:
        key: A string representing an environment variable name.

    Returns:
        String HTML representing the value and variable.
    """
    value = os.getenv(key)
    return KEY_VALUE_TEMPLATE.format(key, value)