class_docstr: A class for representing multivariate rational function fields. 
docstr: Convert SymPy's expression to ``dtype``. 
code: def from_sympy(self, a):
      """Convert SymPy's expression to ``dtype``."""
      return self.field.from_expr(a)
  
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 10 for calling the FractionField obj's underlying member method code with example usage: obj.from_sympy(a) and returns: self