Append all columns of dataframe to a new dataframe

I want to append all columns of a dataframe to a new dataframe with single column.

My Current Dataframe:

|**namelist1**| **namelist2** |  **namelist3** |and so on
|khalid       |  sabbir       | liton          |
|tamim        |  sakib        | tawhid         |
|taskin       |  santo        | naim           |

Expected Dataframe:

**namelistall**
khalid      
sabbir     
liton
tamim       
sakib      
tawhid
taskin      
santo      
naim

>Solution :

Use numpy.ravel with DataFrame constructor:

df = pd.DataFrame({'namelistall': np.ravel(df.to_numpy())})
print (df)
  namelistall
0      khalid
1      sabbir
2       liton
3       tamim
4       sakib
5      tawhid
6      taskin
7       santo
8        naim