toInt

    pub fn toInt(self: Const, comptime Int: type) ConvertError!Int {
        switch (@typeInfo(Int)) {
            .int => |info| {
                // Make sure -0 is handled correctly.
                if (self.eqlZero()) return 0;

                const Unsigned = @Int(.unsigned, info.bits);

                if (!self.fitsInTwosComp(info.signedness, info.bits)) {
                    return error.TargetTooSmall;
                }

                var r: Unsigned = 0;

                if (@sizeOf(Unsigned) <= @sizeOf(Limb)) {
                    r = @intCast(self.limbs[0]);
                } else {
                    for (self.limbs[0..self.limbs.len], 0..) |_, ri| {
                        const limb = self.limbs[self.limbs.len - ri - 1];
                        r <<= limb_bits;
                        r |= limb;
                    }
                }

                if (info.signedness == .unsigned) {
                    return if (self.positive) @intCast(r) else error.NegativeIntoUnsigned;
                } else {
                    if (self.positive) {
                        return @intCast(r);
                    } else {
                        if (math.cast(Int, r)) |ok| {
                            return -ok;
                        } else {
                            return minInt(Int);
                        }
                    }
                }
            },
            else => @compileError("expected int type, found '" ++ @typeName(Int) ++ "'"),
        }
    }