title: How do I concatenate a dataframe and two strings such that it covers all rows in a pandas dataframe?
body: <p>I have two dataframes -</p>
  <pre><code>test_as_df
  Out[52]: 
          SalesForceSubscriberKey  Converted  ... Calls  NumberOfVisits
  0                      10076422          0  ...     0               1
  1                      10076424          0  ...     0               1
  
  preds_as_df
  Out[53]: 
          predict        p0        p1
  0             0  0.996517  0.003483
  1             0  0.999101  0.000899
  
  ModId
  Out[54]: 'GBM_grid'
  
  date
  Out[55]: '2022-06-15'
  </code></pre>
  <p>I am able to concat the first two dataframes using</p>
  <pre><code>dfmodwh = pd.concat([test_as_df, preds_as_df], axis=1)
  </code></pre>
  <p>But when I add ModId and date to this i get -</p>
  <pre><code>TypeError: cannot concatenate object of type '&lt;class 'str'&gt;'; only Series and DataFrame objs are valid
  </code></pre>
  <p>I just want my final df to look like -</p>
  <pre><code>        SalesForceSubscriberKey  Converted     p0        p1   date ModId
  0            10076422          0    0.996517  0.003483      2022-06-15  GBM_grid
  1            10076424          0  0.999101  0.000899       2022-06-15   GBM_grid
  </code></pre>
  <p>The ModId and date columns should have the same values throughout for all the number of rows after  the first two dataframes are concatenated. How do I avoid the error?</p>