code: def __find_caller(stack_info=False):
          
          frame = logging.currentframe()
          # On some versions of IronPython, currentframe() returns None if
          # IronPython isn't run with -X:Frames.
          if frame:
              frame = frame.f_back
  
          caller_info = '(unknown file)', 0, '(unknown function)', None
  
          while hasattr(frame, 'f_code'):
              co = frame.f_code
              if _logone_src in os.path.normcase(co.co_filename):
                  frame = frame.f_back
                  continue
  
              tb_info = None
              if stack_info:
                  with StringIO() as _buffer:
                      _buffer.write('Traceback (most recent call last):\n')
                      traceback.print_stack(frame, file=_buffer)
                      tb_info = _buffer.getvalue().strip()
  
              caller_info = co.co_filename, frame.f_lineno, co.co_name, tb_info
              break
          return caller_info
docs: Find the stack frame of the caller so that we can note the source file name,
          line number and function name.