Constant lexical_util::format::PERL_LITERAL

pub const PERL_LITERAL: u128 = NumberFormatBuilder::new()
    .digit_separator(num::NonZeroU8::new(b'_'))
    .no_special(true)
    .internal_digit_separator(true)
    .fraction_leading_digit_separator(true)
    .exponent_leading_digit_separator(true)
    .trailing_digit_separator(true)
    .consecutive_digit_separator(true)
    .build(); // 0x0000_0a00_0000_005f_0000_0ff7_0000_040cu128

Number format for a Perl literal floating-point number.