I use python2.7 in Linux. From https://docs.python.org/2/howto/unicode.html. I find that python use one byte for each alphabet in str, while it uses 4 bytes in Unicode string. So why I get True after I input '1' == u'1'.
A similar truth in python2:
In [1]: a = {}
In [2]: a['1'] = 1
In [3]: a[u'1']
Out[3]: 1
UTF-8 is capable of encoding all 1,112,064 valid character code points in Unicode using one to four one-byte (8-bit) code units. Code points with lower numerical values, which tend to occur more frequently, are encoded using fewer bytes. It was designed for backward compatibility with ASCII: the first 128 characters of Unicode, which correspond one-to-one with ASCII, are encoded using a single byte with the same binary value as ASCII, so that valid ASCII text is valid UTF-8-encoded Unicode as well.
You can see an example of this:
>>> a = u'1'
>>> a.encode('utf-8')
'1'
>>> b = u'ツ'
>>> b.encode('utf-8')
'\xe3\x83\x84'