Method to take an exception and translate the Python internal traceback into a list
        of the pyparsing expressions that caused the exception to be raised.

        Parameters:

         - exc - exception raised during parsing (need not be a ParseException, in support
           of Python exceptions that might be raised in a parse action)
         - depth (default=16) - number of levels back in the stack trace to list expression
           and function names; if None, the full stack trace names will be listed; if 0, only
           the failing input line, marker, and exception string will be shown

        Returns a multi-line string listing the ParserElements and/or function names in the
        exception's stack trace.

        Note: the diagnostic output will include string representations of the expressions
        that failed to parse. These representations will be more helpful if you use `setName` to
        give identifiable names to your expressions. Otherwise they will use the default string
        forms, which may be cryptic to read.

        explain() is only supported under Python 3.

def explain(exc, depth=16):
        """
        Method to take an exception and translate the Python internal traceback into a list
        of the pyparsing expressions that caused the exception to be raised.

        Parameters:

         - exc - exception raised during parsing (need not be a ParseException, in support
           of Python exceptions that might be raised in a parse action)
         - depth (default=16) - number of levels back in the stack trace to list expression
           and function names; if None, the full stack trace names will be listed; if 0, only
           the failing input line, marker, and exception string will be shown

        Returns a multi-line string listing the ParserElements and/or function names in the
        exception's stack trace.

        Note: the diagnostic output will include string representations of the expressions
        that failed to parse. These representations will be more helpful if you use `setName` to
        give identifiable names to your expressions. Otherwise they will use the default string
        forms, which may be cryptic to read.

        explain() is only supported under Python 3.
        """
        import inspect

        if depth is None:
            depth = sys.getrecursionlimit()
        ret = []
        if isinstance(exc, ParseBaseException):
            ret.append(exc.line)
            ret.append(' ' * (exc.col - 1) + '^')
        ret.append("{0}: {1}".format(type(exc).__name__, exc))

        if depth > 0:
            callers = inspect.getinnerframes(exc.__traceback__, context=depth)
            seen = set()
            for i, ff in enumerate(callers[-depth:]):
                frm = ff.frame

                f_self = frm.f_locals.get('self', None)
                if isinstance(f_self, ParserElement):
                    if frm.f_code.co_name not in ('parseImpl', '_parseNoCache'):
                        continue
                    if f_self in seen:
                        continue
                    seen.add(f_self)

                    self_type = type(f_self)
                    ret.append("{0}.{1} - {2}".format(self_type.__module__,
                                                      self_type.__name__,
                                                      f_self))
                elif f_self is not None:
                    self_type = type(f_self)
                    ret.append("{0}.{1}".format(self_type.__module__,
                                                self_type.__name__))
                else:
                    code = frm.f_code
                    if code.co_name in ('wrapper', '<module>'):
                        continue

                    ret.append("{0}".format(code.co_name))

                depth -= 1
                if not depth:
                    break

        return '\n'.join(ret)