set_columns() equivalent of set_index() ?
Unless I'm missing something, there's no DataFrame method analogous to set_index() for setting column values. One can directly manipulate the .columns attribute of the DF, but it's often convenient to be able to alter columns in-line after some other operation--e.g.,

`data = pd.concat([df_a, df_b], axis=1).set_columns(['a', 'b', 'c'])`

Even if there's already some equivalent longer way to do this, it might be nice to add set_columns for convenience; I've now caught myself trying to call set_columns() on a DF several times.
