A class for fields of rational functions. It is a subclass of nzmath.ring.QuotientField.
if self is a nested RationalFunctionField i.e. its coefficientField is also a RationalFunctionField, then the function returns one level unnested RationalFunctionField.
For example:
RationalFunctionField(RationalFunctionField(Q, "x"), "y").unnest()
returns
RationalFunctionField(Q, sets.Set(["x","y"])).
Inherited from nzmath.ring.Field.
Inherited from nzmath.ring..CommutativeRing.