In [8]: b=b'hello'In [9]: type(b)Out[9]: builtins.bytesIn [10]: s='hello'In [11]: type(s)Out[11]: builtins.str

To convert from str to bytes, use str.encode().:

In [12]: a=str.encode(s)In [13]: type(a)Out[13]: builtins.bytes

To convert from bytes to str, use bytes.decode():

In [14]: c=bytes.decode(a)In [15]: type(c)Out[15]: builtins.str