Merging two rows in pandas to one header cell per column

i have a table in pandas that looks like this:

and what i would like to have a table like this :

how can i merge cells 0 and 1 to one header column?

>Solution :

There is a question about that column '0', if indeed it is one. But if it is not (and is just the index having been pasted slightly incorrectly), then I would do:

newdf = df.iloc[1:].set_axis(df.columns + ' ' + df.iloc[0], axis=1)
>>> newdf
  A header Another header
1    First            row
2   Second            row