In the pandas library many times there is an option to change the object inplace such as with the following statement...
pandas
df.dropna(axis=\'index\
inplace=True is used depending if you want to make changes to the original df or not.
inplace=True
df.drop_duplicates()
will only make a view of dropped values but not make any changes to df
df.drop_duplicates(inplace = True)
will drop values and make changes to df.
Hope this helps.:)