pub fn encode(v: i64, r: u32) -> Option<Vec<u8>>Expand description
v as 10-digit two’s complement in radix 2, 8 or 16: None exactly when
v is outside [−r¹⁰/2, r¹⁰/2). The digits are those of v (v + r¹⁰
if negative) without leading zeros: at most 10, each below r, exactly 10
for a negative v, and decode maps them back to v.