The code provided is:

```
def square():
"""Returns the square of a number."""
squared = n**2
print "%d squared is %d." % (n, squared)
return squared
# Call the square function on line 9! Make sure to
# include the number 10 between the parentheses.
```

This should have allowed me to input:

square(10)

on line 9 and provide me with the answer. Instead, I received an error stating that:

"""Traceback (most recent call last):

File "python", line 9, in *TypeError: square() takes no arguments (1 given)*""" emphasis added

To fix this, I added an """n"""" to the parenthesis. My final working code looked like this:

```
def square(n):
"""Returns the square of a number."""
squared = n**2
print "%d squared is %d." % (n, squared)
return squared
# Call the square function on line 9! Make sure to
# include the number 10 between the parentheses.
square(10)
```