class_docstr: A class for representing rational function fields. 
class_docstr_tok: ["A","class","for","representing","rational","function","fields","."]
docstr: Returns a fraction field, i.e. `K(X)`. 
docstr_tok: ["Returns","a","fraction","field",",","i.e",".","`","K","(","X",")","`","."]
code: def frac_field(self, *gens):
      """Returns a fraction field, i.e. `K(X)`."""
      raise NotImplementedError("nested domains not allowed")
  
imports: from sympy.polys.domains.field import Field
  from sympy.polys.domains.compositedomain import CompositeDomain
  from sympy.polys.polyclasses import DMF
  from sympy.polys.polyerrors import GeneratorsNeeded
  from sympy.polys.polyutils import dict_from_basic, basic_from_dict, _dict_reorder
  from sympy.utilities import public
label_desc: Use image node_id 19 for calling the FractionField obj's underlying member method code with example usage: obj.frac_field() without return types