:   '''[string] cat''' ?''arg''? ?''arg …''?

Returns the concatenation of its arguments in the order that they are given. If there are no arguments, produces the empty string. Does not produce errors.

First entered Tcl in 8.6.2.

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Specified in http://www.tcl.tk/cgi-bin/tct/tip/429.html%|%TIP #429%|%.

A pure-Tcl proof of concept using [ensemble extend]:
======
extend string {
    proc cat args {
        join $args ""
    }
}
======

'string cat' acts as the [identity function] for a single argument (see also: [K]).  For multiple arguments, it concatenates them with no further substitution.

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