```
In [37]:
```def mean_function(num_list):
number_of_elements = 0
sum_of_numbers = 0
for number in num_list:
number_of_elements = number_of_elements + 1
sum_of_numbers = sum_of_numbers + number
mean_of_numbers = sum_of_numbers/number_of_elements
return mean_of_numbers

```
In [43]:
```numbers_list=[1,2,3,4,5]
mean_function(numbers_list)

```
Out[43]:
```