llvm::StringRef equation, RankedTensorType lhs_ty,
    RankedTensorType rhs_ty) {
  llvm::StringRef lhs_rhs;
  llvm::StringRef out;
  std::tie(lhs_rhs, out) = equation.split("->");
  if (lhs_rhs.empty() || out.empty()) return std::nullopt;

  llvm::StringRef lhs;
  llvm::StringRef rhs;
  std::tie(lhs, rhs) = lhs_rhs.split(',');
  if (lhs.empty() || rhs.empty()) return std::nullopt;

				// Collect them for later analysis.
				lhsVars = append(lhsVars, obj)
			}
			check.stmtList(inner, clause.Body)
			check.closeScope()
		}

		// If lhs exists, we must have at least one lhs variable that was used.
		if lhs != nil {
			var used bool
			for _, v := range lhsVars {
				if v.used {
					used = true
				}

			// For the "declared and not used" error, all lhs variables act as
			// one; i.e., if any one of them is 'used', all of them are 'used'.
			// Collect them for later analysis.
			lhsVars = append(lhsVars, obj)
		}
		check.stmtList(inner, clause.Body)
		check.closeScope()
	}

	// If lhs exists, we must have at least one lhs variable that was used.