add info on known floating point problems

DEBUG.md

@@ -24,7 +24,7 @@ throws this:
 ```shell
 SyntaxError: unexpected EOF while parsing
 ```
-Keep it in mind
+Keep it in mind - it will come back to you sooner or later, because missing a closing parenthesis is easy enough.
 
 ### Example (hard)
 
@@ -55,9 +55,13 @@ True or False #???
 ```
 It's quite obvious, isn't it? Try it!
 
-# 
-Problem: What to do, when the error message is crap
-# printf debugger .. or print
+Lessions:
+- understand the type system of your language + their basic methods
+- understand common difficulties of basic types (numbers, strings, ...)
+- **Always-Available-Debugger: your mind + print**
+
+More on floating point problems [here](https://floating-point-gui.de/) of as [pdf](https://www.phys.uconn.edu/~rozman/Courses/P2200_15F/downloads/floating-point-guide-2015-10-15.pdf)
+
 
 # python's own debugger: pdb/pudb