clearNN cleans the first environment ls(.GlobalEnv) from objects 
not listed in donotremove and detach the loaded packages and their 
dependencies not listed in donotdetach.
detachNN() removes ZZ and all objects in ls(.GlobalEnv) 
not listed in donotremove. It does not detach any packages.
1 2 3  | 
donotremove | 
 a vector of characters representing objects in   | 
donotdetach | 
 a vector of packages and environments that are not detached.
  | 
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