code: def export_txt(obj, file_name, two_dimensional=False, **kwargs):
      
      # Check if the user has set any control points
      if obj.ctrlpts is None or len(obj.ctrlpts) == 0:
          raise exch.GeomdlException("There are no control points to save!")
  
      # Check the usage of two_dimensional flag
      if obj.pdimension == 1 and two_dimensional:
          # Silently ignore two_dimensional flag
          two_dimensional = False
  
      # File delimiters
      col_sep = kwargs.get('col_separator', ";")
      sep = kwargs.get('separator', ",")
  
      content = exch.export_text_data(obj, sep, col_sep, two_dimensional)
      return exch.write_file(file_name, content)
docs: Exports control points as a text file.
  
      For curves the output is always a list of control points. For surfaces, it is possible to generate a 2-dimensional
      control point output file using ``two_dimensional``.
  
      Please see :py:func:`.exchange.import_txt()` for detailed description of the keyword arguments.
  
      :param obj: a spline geometry object
      :type obj: abstract.SplineGeometry
      :param file_name: file name of the text file to be saved
      :type file_name: str
      :param two_dimensional: type of the text file (only works for Surface objects)
      :type two_dimensional: bool
      :raises GeomdlException: an error occurred writing the file