    Unset values and attributes of shell variables and functions.
    
    For each NAME, remove the corresponding variable or function.
    
    Options:
      -f	treat each NAME as a shell function
      -v	treat each NAME as a shell variable
    
    Without options, unset first tries to unset a variable, and if that fails,
    tries to unset a function.
    
    Some variables cannot be unset; also see `readonly'.
    
    Exit Status:
    Returns success unless an invalid option is given or a NAME is read-only.
