Strings have a family of methods that answer a question with True or False:

Method	True when every character is...
`.isdigit()`	a digit, 0 to 9
`.isalpha()`	a letter
`.isalnum()`	a letter or a digit
`.isupper()`	upper case (ignoring non-letters)
`.islower()`	lower case (ignoring non-letters)
`.isspace()`	a space, tab or new line

print("2026".isdigit())
print("20.26".isdigit())
print("Ada".isalpha())
print("Ada Lovelace".isalpha())
print("R2D2".isalnum())

Notice that a space isn't a letter, so "Ada Lovelace".isalpha() is False, and a decimal point isn't a digit. An empty string gives False for all of them.