human
I am working on the file "02-programs.ipynb".
The first task is:
How does the function definition work? 
First we need to use the def command:
python
def degrees_to_radians(theta_d):
This command effectively says "what follows is a function". The first word after def will be the name of the function, which can be used to call it later. This follows similar rules and conventions to variables and files (no spaces, lower case, words separated by underscores, etc.).
After the function name, inside brackets, is the list of input parameters. If there are no input parameters the brackets still need to be there. If there is more than one parameter, they should be separated by commas.
After the bracket there is a colon :. The use of colons to denote special "blocks" of code happens frequently in Python program, and we will see it again later.
After the colon, all the code is indented by four spaces or one tab. Most helpful text editors, such as the spyder editor, will automatically indent the code after a function is defined. If not, use the tab key to ensure the indentation is correct. In Python, whitespace and indentation is essential: it defines where blocks of code (such as functions) start and end. In other languages special keywords or characters may be used, but in Python the indentation of the code statements is the key.
The statement on the next few lines in the function documentation, or docstring. 
```python
    """
    Convert an angle from degrees to radians.
...
"""

```
This is optional: it's not needed to make the code run. However, documentation is extremely useful for the next user of the code. As the next user is likely to be you in a week (or a month), when you'll have forgotten the details of what you did, documentation helps you first.
The docstring can be any string within quotes. Using "triple quotes" allows the string to go across multiple lines. The docstring can be rapidly printed using the help function:
Can you write Python program for it?
assistant
#Here follows is a function".

help(degrees_to_radians)