append - Append to variable

       Append  all  of the value arguments to the current value of variable varName.  If varName does not exist,
       it is given a value equal to the concatenation of all  the  value  arguments.   If  varName  indicate  an 2
       element  that  does  not exist of an array that has a default value set, the concatenation of the default 2
       value and all the value arguments will be stored in the array element.  The result of this command is the
       new value stored in variable varName.  This command provides an efficient way to build up long  variables
       incrementally.  For example, “appenda$b” is much more efficient than “seta$a$b” if $a is long.

       Building a string of comma-separated numbers piecemeal using a loop.

              set var 0
              for {set i 1} {$i<=10} {incr i} {
                  append var "," $i
              }
              puts $var
              # Prints 0,1,2,3,4,5,6,7,8,9,10

       append, variable

Tcl                                                                                                 append(3tcl)

       append - Append to variable

concat(3tcl), lappend(3tcl)

appendvarName ?valuevaluevalue...?
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