Noneに対してメソッドを呼び出した原因と直し方

 1  import re
 2  m = re.match(r"[0-9]+", _____)
                              ^
 3  print(m.group())

Traceback (most recent call last): File "main.py", line 3, in <module> print(m.group()) ^^^^^^^ AttributeError: 'NoneType' object has no attribute 'group'