if check.recordTypes() {
						sig := makeSig(S, S, y.typ)
						sig.variadic = true
						check.recordBuiltinType(call.Fun, sig)
					}
					x.mode = value
					x.typ = S
					break
				}
			}
		}

		// check general case by creating custom signature
		sig := makeSig(S, S, NewSlice(T)) // []T required for variadic signature
		sig.variadic = true

				tparams: t.tparams,
				// instantiated signatures have a nil scope
				recv:     recv,
				params:   params,
				results:  results,
				variadic: t.variadic,
			}
		}

	case *Union:
		terms, copied := subst.termlist(t.terms)
		if copied {
			// term list substitution may introduce duplicate terms (unlikely but possible).

				tparams: t.tparams,
				// instantiated signatures have a nil scope
				recv:     recv,
				params:   params,
				results:  results,
				variadic: t.variadic,
			}
		}

	case *Union:
		terms, copied := subst.termlist(t.terms)
		if copied {
			// term list substitution may introduce duplicate terms (unlikely but possible).

					return false
				}
			}

			yparams = check.subst(nopos, y.params, smap, nil, ctxt).(*Tuple)
			yresults = check.subst(nopos, y.results, smap, nil, ctxt).(*Tuple)
		}

		return x.variadic == y.variadic &&
			c.identical(x.params, yparams, p) &&
			c.identical(x.results, yresults, p)

	case *Union:
		if y, _ := y.(*Union); y != nil {
			// TODO(rfindley): can this be reached during type checking? If so,

					return false
				}
			}

			yparams = check.subst(nopos, y.params, smap, nil, ctxt).(*Tuple)
			yresults = check.subst(nopos, y.results, smap, nil, ctxt).(*Tuple)
		}

		return x.variadic == y.variadic &&
			c.identical(x.params, yparams, p) &&
			c.identical(x.results, yresults, p)

	case *Union:
		if y, _ := y.(*Union); y != nil {
			// TODO(rfindley): can this be reached during type checking? If so,

			hash += h.Hash(f.Type())
		}
		return hash

	case *types.Pointer:
		return 9067 + 2*h.Hash(t.Elem())

	case *types.Signature:
		var hash uint32 = 9091
		if t.Variadic() {
			hash *= 8863
		}

		// Use a separate hasher for types inside of the signature, where type
		// parameter identity is modified to be (index, constraint). We must use a

        };
    if (tf_op->hasTrait<mlir::OpTrait::AttrSizedOperandSegments>() ||
        tf_op->hasTrait<mlir::OpTrait::AttrSizedResultSegments>()) {
      // The op has multiple variadic operands or results.
      // Calculate operand and result segment sizes using the OpDef.
      tensorflow::NameRangeMap input_ranges, output_ranges;
      // This will fail only if the OpDef is syntactically invalid.

		// and result values, corresponding parameter and result types unify,
		// and either both functions are variadic or neither is.
		// Parameter and result names are not required to match.
		// TODO(gri) handle type parameters or document why we can ignore them.
		if y, ok := y.(*Signature); ok {
			return x.variadic == y.variadic &&
				u.nify(x.params, y.params, emode, p) &&
				u.nify(x.results, y.results, emode, p)
		}

}

func (r *importReader) signature(recv *types.Var, rparams, tparams []*types.TypeParam) *types.Signature {
	params := r.paramList()
	results := r.paramList()
	variadic := params.Len() > 0 && r.bool()
	return types.NewSignatureType(recv, rparams, tparams, params, results, variadic)
}

func (r *importReader) tparamList() []*types.TypeParam {
	n := r.uint64()
	if n == 0 {
		return nil
	}
	xs := make([]*types.TypeParam, n)

		// and result values, corresponding parameter and result types unify,
		// and either both functions are variadic or neither is.
		// Parameter and result names are not required to match.
		// TODO(gri) handle type parameters or document why we can ignore them.
		if y, ok := y.(*Signature); ok {
			return x.variadic == y.variadic &&
				u.nify(x.params, y.params, emode, p) &&
				u.nify(x.results, y.results, emode, p)
		}