Append an empty dataframe to a list of dataframes using for loop in python

[Jack]

I have the following 3 dataframes:

I want to append df_forecast to each of df2_CA and df2_USA using a for-loop. However when I run my code, df_forecast is not appending: df2_CA and df2_USA appear exactly as shown above.

Here’s the code:

df_list=[df2_CA, df2_USA] 
 
for x in df_list:
     pd.concat([x, df_forecast]) 
     x['prod'].fillna(method='ffill',inplace=True)     
     x['country'].fillna(method='ffill',inplace=True)
     x.loc['2020-03':'2020-05', 'rev'] = 200

And here is the desired result:

What's wrong with my code?

[User16764241763]

@Jack Homareau​  Can you try union functionality with dataframes?

https://sparkbyexamples.com/pyspark/pyspark-union-and-unionall/

and then try to fill NaNs with the desired values?