code: def get_v_max(self):
      return self._v_max
  
imports: from sympy.core.singleton import S
  from sympy.core.symbol import Symbol
  from sympy.core.sympify import sympify
  from sympy.core.numbers import Integer
label_desc: Use image node_id 7 for calling the PlotInterval obj's underlying member method code with example usage: obj.get_v_max() and returns: self