.....:~==*                                          *==~:.....
......:~==                                          ==~:......
.......:~=                                          =~:.......
........:~                                          ~:........
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........:~                   body                   ~:........
.......:~= ................::====::................ =~:.......
......:~==                                          ==~:......
.....:~==*            a body is a vessel            *==~:.....
....:~==*#            a body is a vessel            #*==~:....
...:~==*#¶            a body is a vessel            ¶#*==~:...
..:~==*#¶#            a body is a vessel            #¶#*==~:..
.:~==*#¶##            a body is a vessel            ##¶#*==~:.
..:~==*#¶#            a body is a vessel            #¶#*==~:..
...:~==*#¶            a body is a vessel            ¶#*==~:...
....:~==*#            a body is a vessel            #*==~:....
.....:~==*            a body is a vessel            *==~:.....
......:~==                                          ==~:......
.......:~=                                          =~:.......
........:~                                          ~:........
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........:~                                          ~:........