parser.rs:
use super::{Color, ImageFormat};
use std::str::from_utf8;
use std::str::FromStr;

pub fn parse_version(input: &[u8]) -> nom::IResult<&[u8], ImageFormat> {
    use nom::branch::alt;
    use nom::bytes::complete::tag;
    use nom::character::complete::line_ending;
    use nom::combinator::map;
    use nom::sequence::terminated;