[Zope] Links between DTML language and Python language...

Hello all, In the last mail I sent, I explaint my problem to know if a specified item is in a list. Oleg helped me and said that : "Learn Python". Now, I wonder if there are strong links between DTML language and Python language. Because, in the DTML language reference, you can find nothing meaning that. Sometimes, I see functions used in DTML which are not referenced in DTML language reference. I guess that it's Python functions. So, I ask the question if it's advised to be introduced to Python before programming in DTML. I would like to know too, if there is any rule that specify how to use Python functions in DTML language, and if all Python functions are accessible in DTML... Thanks, Fred