docs: def _pretty_alignment_out_file_name(self):
          """Checks file name is set for pretty alignment output.
             Returns absolute path."""
          if self.Parameters['-E'].isOn():
              pretty_alignment = self._absolute(str(self.Parameters['-E'].Value))
          else:
              raise ValueError(
                  "No pretty-=alignment (flag -E) output path specified")
          return pretty_alignment