code: def from_pubkey(cls: Type[CRCPubkeyType], pubkey: str) -> CRCPubkeyType:
          
          hash_root = hashlib.sha256()
          hash_root.update(base58.b58decode(pubkey))
          hash_squared = hashlib.sha256()
          hash_squared.update(hash_root.digest())
          b58_checksum = ensure_str(base58.b58encode(hash_squared.digest()))
  
          crc = b58_checksum[:3]
          return cls(pubkey, crc)
docs: Return CRCPubkey instance from public key string
  
          :param pubkey: Public key
          :return: