Function format_int_padded 

fn format_int_padded(
    output: &mut (impl Write + ?Sized),
    value: u64,
    width: u8,
) -> Result<usize>

Write an integer with zeros as trailing padding if necessary to reach the requested width.

This function is intended to be used for formatting the fractional part of a value, as the trailing zeros would change the semantic meaning for non-fractional values.