docs: def to_string(self, buf=None, format_abs_ref_as='string',
                    upper_triangle=True, header=True, index=True, **kwargs):
          """Render a DataFrame to a console-friendly tabular output.
  
          Wrapper around the :meth:`pandas.DataFrame.to_string` method.
          """
          out = self._sympy_formatter()
          out = out._abs_ref_formatter(format_as=format_abs_ref_as)
          if not upper_triangle:
              out = out._remove_upper_triangle()
  
          content = out._frame.to_string(buf=buf, header=header, index=index,
                                         **kwargs)
          if not index and not header:
              # NOTE(the following might be removed in the future
              # introduced because of formatting bug in pandas
              # See https://github.com/pandas-dev/pandas/issues/13032)
              space = ' ' * (out.loc[:, 'atom'].str.len().max()
                             - len(out.iloc[0, 0]))
              content = space + content
          return content