Creating a list of hyperlinks in Python

The error positional argument follows keyword argument that you're getting is due the way you're passing the arguments to the page.format() function.

In your first example link argument is a bunch of strings separated by the comma. But only the first line:

link = '<a href="fatalities_per_year.html">A Look at Death Rates Over the Years</a>'

is recognized as keyword argument named link, rest of the lines are treated like positional arguments without keyword assigned to them. This is a violation in Python, positional (not named arguments) can only be used before keyword (named) arguments, thus an error.

In your second example you are trying to pass multiline string as link argument but you use single quotes to do this. In order to use multiline string in Python you must enclose it in triple quotes

some_string = """line 1
line 2"""

The easiest fix for you would be to do:

out = open("index.html", "w")

out.write(page.format(
heading = "<h1>Road Fatalities in Australia</h1>", 
contents1 = "<p>On this site you will find road fatality statistical data.</p>", 
contents2 = "<p>...</p>", 
contents3 = "<p>...</p>", 
link = '''<ul>
    <li><a href="fatalities_per_year.html">A Look at Death Rates Over the Years</a></li>
    <li><a href="fatalities_per_state.html">Which State has the Highest Fatality Rate?</a></li>
    <li><a href="fatalities_per_day.html">Which Day of the Week is Deadliest?</a></li>
    <li><a href="fatalities_per_time.html">Which Time of Day is the Deadliest?</a></li>
    <li><a href="fatalities_trucks.html">How Many Trucks are in Fatal Crashes</a></li>
    <li><a href="fatalities_speed_zones.html">Which Speed Zones are the Deadliest?</a></li>
    <li><a href="fatalities_gender.html">Does Your Gender Increase the Risk of Dying?</a></li>
    <li><a href="fatalities_age.html">Does Your Age Have Anything to do With Death-rates?</a></li>
    <li><a href="fatalities_user.html">Fatality Data</a></li>
</ul>'''))
out.close()

Which would create:

<h1>Road Fatalities in Australia</h1>
<p>On this site you will find road fatality statistical data.</p>
<p>...</p>
<p>...</p>
<ul>
    <li><a href="fatalities_per_year.html">A Look at Death Rates Over the Years</a></li>
    <li><a href="fatalities_per_state.html">Which State has the Highest Fatality Rate?</a></li>
    <li><a href="fatalities_per_day.html">Which Day of the Week is Deadliest?</a></li>
    <li><a href="fatalities_per_time.html">Which Time of Day is the Deadliest?</a></li>
    <li><a href="fatalities_trucks.html">How Many Trucks are in Fatal Crashes</a></li>
    <li><a href="fatalities_speed_zones.html">Which Speed Zones are the Deadliest?</a></li>
    <li><a href="fatalities_gender.html">Does Your Gender Increase the Risk of Dying?</a></li>
    <li><a href="fatalities_age.html">Does Your Age Have Anything to do With Death-rates?</a></li>
    <li><a href="fatalities_user.html">Fatality Data</a></li>
</ul>

given that

page = """{heading}
{contents1}
{contents2}
{contents3}
{link}"""