     let middle = runs[i].lowerBound
     let high = runs[i].upperBound
     
-    let result = try _merge(
+    try _merge(
       low: baseAddress! + low,
       mid: baseAddress! + middle,
       high: baseAddress! + high,

      }
      
      // Merge the runs at `i` and `i - 1`.
      result = try result && _mergeRuns(
        &runs, at: lastIndex, buffer: buffer, by: areInIncreasingOrder)
    }

    return result
  }
  
  /// Merges elements of `runs` until only one run remains.

  ///   `min(runs[i].count, runs[i - 1].count)` uninitialized elements.
  /// - Precondition: The ranges in `runs` must be consecutive, such that for
  ///   any i, `runs[i].upperBound == runs[i + 1].lowerBound`.
  @discardableResult
  @inlinable
  public mutating func _mergeTopRuns(
    _ runs: inout [Range<Index>],
