READ IF MISSING ☆☆
`READ IF MISSING THEN EXIT DO: variables
READ IF MISSING THEN EXIT FOR: variables
READ IF MISSING THEN line_number: variables
`
A READ statement can contain the instruction that is to be executed on the exhaustion of data.
The instruction is one of EXIT DO, EXIT FOR, or a line number.
Example.

    10 DATA 1,2,3
    20 DO
    30    READ IF MISSING THEN EXIT DO: A
    40    PRINT A,A^2
    50 LOOP
    60 END