pd.options.mode.chained_assignment = None  # default='warn'

Here is what the above code is Doing:
1. Importing the pandas library
2. Importing the numpy library
3. Importing the matplotlib.pyplot library
4. Setting the default figure size
5. Setting the default font size
6. Setting the default style for matplotlib
7. Turning off the warning that displays when you try to create a new column based on an existing column in a dataframe.