Construct an output path string from an input path string.
        :param str input_path: Input path string.
        :return: Output path string.
        :rtype: :py:class:`str`

def _output_path(self, input_path, to_format, archive=False):
        """Construct an output path string from an input path string.
        :param str input_path: Input path string.
        :return: Output path string.
        :rtype: :py:class:`str`
        """
        indirpath, fname = os.path.split(os.path.abspath(os.path.normpath(input_path)))

        commonprefix = os.path.commonprefix([os.path.abspath(self.file_generator.from_path),
                                             os.path.abspath(indirpath)])

        commonparts = commonprefix.split(os.sep)
        inparts = indirpath.split(os.sep)
        outparts = inparts[len(commonparts):]

        if archive:
            outdirpath = os.path.join(*outparts) if outparts else ""
        else:
            outdirpath = os.path.join(self.file_generator.to_path, *outparts)

        return os.path.join(outdirpath, fname + self.file_generator.file_extension[to_format])