def decode_addr(v):
 if (len(v) not in [0, 20]):
  raise Exception('Serialized addresses must be empty or 20 bytes long!')
 return encode_hex(v)

def decode_addr ( v ) : if ( len ( v ) not in [ 0 , 20 ] ) : raise Exception ( 'Serialized addresses must be empty or 20 bytes long!' ) return encode_hex ( v )
decodes an address from serialization .