Constant lexical_parse_integer::format::CXX17_LITERAL

pub const CXX17_LITERAL: u128 = NumberFormatBuilder::new().digit_separator(num::NonZeroU8::new(b'\'')).case_sensitive_special(true).internal_digit_separator(true).build(); // 202_824_096_037_236_127_258_377_250_146_316u128

Number format for a C++17 literal floating-point number.