As many of the world's leaders sit down to talk policy and diplomacy in Hamburg this week, it presents a rather interesting opportunity for some comparisons.
As every great democracy knows, change is inevitable - leaders cannot stay in power forever - so when the old guard leave and their replacements attend events such as this, it's rather fascinating to see how the rest of the pack reacts.
A prime example of this would be Angela Merkel's reaction to two US President's.
Mrs Merkel has been Chancellor of Germany since 2005, and has therefore worked closely with Barack Obama and is now set to work with Donald Trump.
Here are just a few comparisons between Donald Trump with Angela Merkel and Barack Obama with Angela Merkel.
1. Shaking hands
Here's Obama and Merkel shaking hands on his 2016 trip to Berlin
Here's Trump and Merkel shaking hands at the G20 summit
2. Discussing politics
Here's Obama and Merkel strategising the G20 summit in China in 2016
Here's Trump and Merkel strategising at the G20 Summit in Hamburg this week
3. Listening to each other
Here's Merkel listening to Trump at the G20
Here's Merkel listening to Obama
4. Hanging with another world leader
Here's Merkel with Trump with a group of other leaders.
Here's Merkel with Obama and another foreign leader
5. Holding a joint press conference
Here's Merkel listening to Trump
And here's Merkel listening to Obama
6. At the White House
Here's Merkel and Trump at the White House.
Here's Obama and Merkel.