Function make_num 

pub(crate) fn make_num(
    digits: &str,
    hasdot: bool,
    state: NumeralMode,
) -> Result<Unsigned36Bit, StringConversionFailed>

Convert a string to an Unsigned36Bit.

Combining state and hasdot

state	hasdot	Conversion Base
NumeralMode::Octal	false	Octal
NumeralMode::Decimal	false	Decimal
NumeralMode::Octal	true	Decimal
NumeralMode::Decimal	true	Octal

Arguments

• digits - the octal or decimal digits
• hasdot - if true, the input has a trailing dot (not in digits).
• state - indicates whether the default mode is octal or decimal.

TODO: consider just having the caller call make_u36() directly.