Result Codes
TCL_OK - the command executed normally with the given result.
TCL_ERROR - the command executed with an error, which is described in result.
TCL_RETURN - the command requests the current procedure return, result has the return value.
TCL_BREAK - the command requests that the innermost loop be exited, the result is meaningless.
TCL_CONTINUE - the command requests that the caller go on to the next iteration of the current loop, the result is meaningless.