> For the complete documentation index, see [llms.txt](https://roxy-wong.gitbook.io/pcep-30-02-practice-test-compendium/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://roxy-wong.gitbook.io/pcep-30-02-practice-test-compendium/part-2-or-study-pages-and-exam-section-questions/exam-block-4-functions-and-exceptions/module-01/1.1.1-pcep-30-02-practice-test-compendium-exam-block-4/1.2.1.2-pcep-30-02-practice-test-compendium-functions.md).

# 1.2.1.2 PCEP-30-02 Practice Test Compendium – Functions

## Functions – continued

10\) A function definition can declare **default values** for some or all of its parameters. When the invocation does not provide arguments for these parameters, the default values are taken into consideration. Note: parameters with default values must not precede the ones without them. For example, the following snippet prints `1 2 3` to the screen:

```python
def function(a, b, c):
    print(a, b, c)


function(1, c=3, b=2)
```

11\) Note that the following invocation is incorrect and will raise the `TypeError` exception, because the a parameter is set twice (once with the positional passing and once with the keyword passing) while the `c` parameter is not set at all.

```python
function(1, a=1, b=2)
```

12\) A **scope** is the part of the code where a certain name is properly recognizable.

13\) A variable existing outside a function has a scope which includes the function's bodies.

14\) A variable defined inside the function has a scope inside the function's body only.

15\) If a certain variable is used inside a function and the variable’s name is listed as an argument of the `global` keyword, it has **global scope**, and it is also recognizable outside the function. For example, the following snippet outputs `2` to the screen:

```python
def function():
    global variable
    variable += 1


variable = 1
function()
print(variable)
```

Note: removing the line containing the `global` keyword will spoil the code and the `UnboundLocalError` exception will be raised.

16\) Changing the parameter's value **doesn't propagate it** outside the function. For example, the following snippet outputs `[1]` to the screen:

```python
def function(parameter):
    parameter = [2]


the_list = [1]
function(the_list)
print(the_list)
```

17\) If the parameter is a **list** or a **dictionary**, changing its contents **propagates them** outside the function. For example, the following snippet outputs `[2]` to the screen:

```python
def function(parameter):
    parameter[0] = 2


the_list = [1]
function(the_list)
print(the_list)
```

18\) **Recursion** is a programming technique in which the function **invokes itself** to perform a complex task. For example, the following snippet contains a function that evaluates the factorial of its argument and prints `120` to the screen:

```python
def factorial(n):
    if n < 2:
        return n
    else:
        return n * factorial(n - 1)


print(factorial(5))
```