code: def show(self):
      if not base_backend._show:
          return
      if len(self._series) != 1:
          raise ValueError(
              "The TextBackend supports only one graph per Plot."
          )
      elif not isinstance(self._series[0], LineOver1DRangeSeries):
          raise ValueError(
              "The TextBackend supports only expressions over a 1D range"
          )
      else:
          ser = self._series[0]
          textplot(ser.expr, ser.start, ser.end)
  
file_path: sympy/sympy/plotting/backends/textbackend/text.py
imports: import sympy.plotting.backends.base_backend
  from sympy.plotting.series import LineOver1DRangeSeries
  from sympy.plotting.textplot import textplot
label_desc: Use image node_id 2 for calling the TextBackend obj's underlying member method code with example usage: obj.show() without return types