[Features] To define user function.

 [Format] FUNC funcname[$](variable[$][,variable[$]]...)   :ENDFUNC [retvalue]

    To define User function.
    The function name and variables used are specified.
    When dealing with string return value, '$' is put to func-name end. (cf. line 130)
    The arguments been placement into brackets according to the number.
    If the argument is in string type, '$' is put to the variable-name end.
    It return to original position by 'ENDFUNC'.
    Return value is written behind 'ENDFUNC'. (if omit return 0 or Null-string)
    It is called in this form. [ a=fname(var1,var2) ]
    The variable which appeared by the inner side of the function is defined as local variable.
    Even if the original global variable is used with local scope, it is still global.
    The function definition can be placement anywhere.

 [e.g.]  [smp_func.bas]
    10 d=4
    20 f=pow(8,d)
    30 print f
    40 st$=initial$("android")
    50 print st$
    100 func pow(a,b)
    110  c=a^b
    120 endfunc c
    130 func initial$(s$)
    140  if len(s$)>0 then r$=left$(s$,1)
    150 endfunc r$

   ' This case
   ' Global d, (f, st$ :This variable of call, it define after returning from the function)
   ' Local  a, b, c, s$, r$


    The notes of the global variable definition position.

    10 f=ts()
    30 func ts()
    50 print d1;d2
    60 endfunc

    Although the variables d1,d2 are in the position of global variable in this example,
    When the user function is called for instruction execution time by line[10],
     it doesn't define automatically yet.
    So it becomes treatment of local variable when it appeared in [line40].

    Because the variable'f'[line10] which receive return-value is also in the state
     which isn't defined at the time of ts()-function call.
    (It is defined when be back and timing substituted)

    The global variable used with user function,
     please be sure to define beforehand as global variable
     before it is called function[line10] and it is defined function[line30],
    Like below example.

    20 f=ts()
    30 func ts()
    50 print d1;d2
    60 endfunc


 [Features] According to the value of a formula, execution moves to an applied command group.

 [Format] SELECT CASE expression:  CASE a:  END SELECT

    To execution one of several groups of statements, depending on the value of 'expression'.
    'case else' is selected when applied to nothing.
    The data treated by 'expression' also support string variable & constant.

 [e.g.] [smp_select.bas]
    10 input dat
    20 select case dat
    30  case 1:
    40   color col(15)
    50   print "First"
    60  case 2:
    70   color col(7)
    80   print "second"
    90  case else:
    100   color col(2)
    110   print "Other"
    120 end select