Moves the pointer in a
.fmt file to a particular row.
fh (scalar) – file handle of an open file.
r (scalar) – the row number to which the pointer is to be moved.
y (scalar) – the row number to which the pointer has been moved.
If r = -1, the current row number will be returned.
If r = 0, the pointer will be moved to the end of the file, just past the end of the last row.
rowsf() returns the number of rows in a file.
seekr(fh, 0) == rowsf(fh) + 1;