def line_history
      support! :line_stats

      history = { :additions => [], :deletions => [] }
      values.reverse.each do |commit|
        history[:additions] <<  commit.additions
        history[:deletions] << -commit.deletions
      end

      history
    end
def line_history
      support! :line_stats

      history = { :additions => [], :deletions => [] }
      values.reverse.each do |commit|
        history[:additions] <<  commit.additions
        history[:deletions] << -commit.deletions
      end

      history
    end
This evaluates the changed lines in each commit of this collection

 For easier use, the values are stored in separate arrays where each
 number represents the number of changed (i.e. added or deleted) lines in
 one commit.

 @example
  commits.line_history
  => { :additions => [10, 5, 0], :deletions => [0, -2, -1] }
 @return [Hash<Symbol, Array>] Added lines are returned in an `Array`
         assigned to key `:additions`, deleted lines are assigned to
         `:deletions`
 @see Commit#additions
 @see Commit#deletions