class_docstr: A class for representing multivariate rational function fields. 
code: def one(self):
      return self.field.one
  
imports: from sympy.polys.domains.compositedomain import CompositeDomain
  from sympy.polys.domains.field import Field
  from sympy.polys.polyerrors import CoercionFailed, GeneratorsError
  from sympy.utilities import public
label_desc: Use image node_id 4 for calling the FractionField obj's underlying member method code with example usage: obj.one() and returns: self