Function shift_reader 

pub fn shift_reader<R: Read>(
    reader: BufReader<R>,
    shift: i64,
    plus_shift: i64,
    minus_shift: i64,
    genome: Option<&HashMap<String, u64>>,
    output: &mut dyn Write,
) -> Result<()>

Shift BED records from reader by shift bases, write to output.

plus_shift / minus_shift — per-strand overrides; set equal to shift to disable strand-aware mode. genome — when Some, coordinates are clamped and off-end records dropped.