WTF is a Python library that tries to help you understand where things came from. It's intended for manual tracing of executing programs. Anywhere one would otherwise be using print statetments, one can instead use wtf statements.
Simply calling wtf() defaults to printing the name of the current function and wtf line number and the function names and line numbers of the previous four stack frames.
You can configure where output gets written to, how many stack frames to examine, and whether or not to inspect variable declarations as it walks up the stack.