start to feature Russian presidents Boris Yeltsin, Vladimir Putin, and Dmitry Medvedev. Most sets feature the current leader as the largest doll, with the predecessors decreasing in size. The remaining smaller dolls may feature other former leaders such as Leonid Brezhnev, Nikita Khrushchev, Joseph Stalin, Vladimir Lenin, and sometimes several historically significant Tsars such as Nicholas II and Peter the Great. Yuri Andropov and Konstantin Chernenko rarely appear due to the short length of their respective terms. Some less-common sets may feature the current leader as the smallest doll, with the predecessors increasing in size, usually with Stalin or Lenin as the largest doll. Some sets that include Yeltsin preceding Gorbachev were made during the brief period between the establishment of President of the RSFSR and the collapse of the Soviet Union, as both Yeltsin and Gorbachev were concurrently in prominent government positions. During Medvedev's presidency, Medvedev and Putin may both share the largest doll due to Putin still having a prominent role in the government as Prime Minister of Russia. As of Putin's re-election as the fourth President of Russia, Medvedev will usually succeed Yeltsin and precede Putin in stacking order, due to Putin's role solely as the largest doll. Political matryoshkas usually range between five and ten dolls per set. World record The largest set of matryoshka dolls in the world is a 51-piece set hand-painted by Youlia Bereznitskaia of Russia, completed in 2003. The tallest doll in the set measures ; the smallest, . Arranged side-by-side, the dolls span . As metaphor Matryoshka is often seen as a symbol of the feminine side of Russian culture. Matryoshka is associated in Russia with family and fertility. Matryoshka is used as the symbol for the epithet Mother Russia. Matryoshka dolls are a traditional representation of the mother carrying a child within her and can be seen as a representation of a chain of mothers carrying on the family legacy through the child in their womb. Furthermore, matryoshka dolls are used to illustrate the unity of body, soul, mind, heart, and spirit. Matryoshkas are also used metaphorically, as a design paradigm, known as the "matryoshka principle" or "nested doll principle". It denotes a recognizable relationship of "object-within-similar-object" that appears in the design of many other natural and crafted objects. Examples of this use include the matrioshka brain, the Matroska media-container format, and the Russian Doll model of multi-walled carbon nanotubes.