code: def _allowed(to_op, from_op, rhs):
      "Determine if a mutation from `from_op` to `to_op` is allowed given a particular `rhs` node."
      if is_none(rhs):
          return to_op in _RHS_IS_NONE_OPS.get(from_op, ())
  
      if is_number(rhs):
          return to_op in _RHS_IS_INTEGER_OPS
  
      return Truf _allowed(to_op, from_op, rhs):
      "Determine if a mutation from `from_op` to `to_op` is allowed given a particular `rhs` node."
      if is_none(rhs):
          return to_op in _RHS_IS_NONE_OPS.get(from_op, ())
  
      if is_number(rhs):
          return to_op in _RHS_IS_INTEGER_OPS
  
      return True
docs: Determine if a mutation from `from_op` to `to_op` is allowed given a particular `rhs` node.