Error in code no of columns not same

Screen Link:

https://app.dataquest.io/m/347/working-with-missing-and-duplicate-data/3/correcting-data-cleaning-errors-that-result-in-missing-values
My Code:
happiness2017.columns = happiness2017.columns.str.replace(’.’, ’ ‘).str.replace(’\s+’, ’ ‘).str.strip().str.upper()
happiness2016.columns = happiness2016.columns.str.replace(’(’,’’).str.replace(’)’,’’).str.strip().str.upper()
happiness2015.columns = happiness2015.columns.str.replace(’(’, ’ ‘).str.replace(’)’,’’).str.strip().str.upper()
combined=pd.concat([happiness2015,happiness2016,happiness2017],ignore_index=True)
missing=combined.isnull().sum()

Replace this line with your code

What I expected to happen:
In combined data frame , 17 columns are expected

What actually happened:
20 columns are coming

Replace this line with the output/error

I am unable to understand although my code appears same as the answer but still no of columns are not same .

  1. Check the output of your missing Series.
  2. See which column names seem “off”. You will notice them soon enough. Focus on what missing should contain and what seems to not match with the expectations.
  3. Think about why those column names are “off”.
  4. Check your code based on the above to try and find out the source of the problem.

At any point you feel stuck and can’t move ahead, try to be specific about how you explored/answered the above points and feel free to ask more questions here.