4-3-1-3 文字列の内容チェック
①isalpha
print("abc".isalpha())
->True
print("abc123".isalpha())
->False
②isdigit
print("123".isdigit())
->True
print("abc123".isdigit())
->False
③isalnum
print("abc123".isalnum())
->True
print("abc123#$%".isalnum())
->False
④islower
print("abc".islower())
->True
print("abcXYZ".islower())
->False
⑤isupper
print("ABC".isupper())
->True
print("ABCxyz".isupper())
->False