class_docstr: Represents a ring domain. 
class_docstr_tok: ["Represents","a","ring","domain","."]
code: def is_unit(self, a):
      try:
          self.revert(a)
          return True
      except NotReversible:
          return False
  
file_path: sympy/sympy/polys/domains/ring.py
imports: from sympy.polys.domains.domain import Domain
  from sympy.polys.polyerrors import ExactQuotientFailed, NotInvertible, NotReversible
  from sympy.utilities import public
label_desc: Use image node_id 8 for calling the Ring obj's underlying member method code with example usage: obj.is_unit(a) and returns: True, False