python - Pandas Version 12 - add new 'column' to series -

See pad 0.12, how do I add a new area for a series ? Import

The syntax given below works for 13 more, but fails for 12:

  b ['new_col'] = 123 Error: 'new_col not in this series!  

Parallel, works for ver = below> = 13 but then fails in version 12:

  b.loc ['new_col' ] = 123 Error: 'New_col'  

Finally I tried to do this, it does not give any error, but does not add new field-value pair:

How can I add this new column to the b series in panda version 12?

  b.set_value ('new_col', 123)  

?