tf.concat reversed arguments?

I’m reading through some academic code and I’ve come across a
line that looks like this

gen1 = tf.concat(3, [gen1, e6]) 

According to the Tensorflow
documentation, the signature is

tf.concat( values, axis, name='concat' ) 

which means the line I found doesn’t make any sense. I thought
that perhaps it was different in an older version, but it’s the
same in the
Tensorflow 1 documentation too!

When I switch the arguments, it works. Is there any explanation
for this madness?