Doubt from polymers

Why Nylon 6 is condensation polymer?
It has bi functional group but it do not release any by product. What's the role of H2O in it's preparation ,need help?

Nylon 6 is a homopolymar Bro

For preparing condensation polymers we need two or more different bi-functional or tri-functional monomeric units
In nylon 6 we have only one unit
6-aminohexanoic acid
Which rearrange itself And release H2O

Ncert mention it as a condensation polymer. So, there is no doubt.
Well what u have mentioned @Satyendra_2019 bro there is no word like we need two or three different bi functional group in the definition.
But please show your work to release H2O, I really can't figure out from where would water releases.

In my Allen modue it says it a homopolymer
But I say think it's a condensed polymer

It's monomer is Caprolactum.