homework

Create a function that returns True if the given string has any of the following:

• Only letters and no numbers.

• Only numbers and no letters.

If a string has both numbers and letters or contains characters that don't fit into any category, return False.

Examples:

• csAlphanumericRestriction("Bold") ➞ True

• csAlphanumericRestriction("123454321") ➞ True

• csAlphanumericRestriction("H3LL0") ➞ False

Notes:

• Any string that contains spaces or is empty should return False.

• [execution time limit] 4 seconds (py3)

• [input] string input_str

• [output] boolean