>>> s = "２34"  # "2" is a double-byte integer
>>> if u"2" in s:
      print "y"

>>> if u"２" in s:
      print "y"

    y
>>> print s[0]

>>> print s[:2]
    ２
>>> print s[:3]
    ２3

text = incoming_bytes.decode("shift_jis")
# ... do stuff ...
outgoing_bytes = text.encode("shift_jis")

>>> import re
>>> s = u"２34"
>>> digit = re.compile(r"d", re.U)
>>> for d in re.findall(digit, s):
...     print d,
...
２ 3 4
>>> wdigit = re.compile(u"[０-９]+")
>>> for wd in re.findall(wdigit, s):
...     print wd,
...
２

ord("２")

65298

def convert_two_byte_numbers(character: str):
    if ord(character) in range(65296, 65306):
        return chr(ord(character) - 65248)
    else:
        return character