whole_func_string: function ascendingSourceBreadth (a, b) {
      return ascendingBreadth(a.source, b.source) || a.index - b.index
    }
func_code_string: function ascendingSourceBreadth (a, b) {
      return ascendingBreadth(a.source, b.source) || a.index - b.index
    }
func_documentation_string: sort links' breadth (ie top to bottom in a column), based on their source nodes' breadths