= f command
        .re-display from top of the hidden lines.
        .xx-xx format is not supported.

      (1) x[n] pattern

       .display top 3 lines
            0001000|A
            f3     |-     13 line excluded ------------------------------
            0015000|O
        ===>
            0001000|A
            0002000|B
            0003000|C
            0004000|D
            -------|-     10 line excluded -----------------------
            0015000|O

      (2) x[n][,b][.s] pattern

        .repaet 3 times that display 2 lines with intermediate 1 line left.

            0001000|A
            f3,2.1 |-     13 line excluded ---------------
            0015000|O
        ===>
            0001000|A
            0002000|B
            0003000|C
            -------|-      1 line excluded ----------------
            0005000|E
            0006000|F
            -------|-      1 line excluded ----------------
            0008000|H
            0009000|I
            -------|-      5 line excluded ----------------
            0015000|O