entrust.py

def checkPin(pinChecked) -> bool:
    """
    Check if the provided PIN is valid.

    A valid PIN is defined as a string of exactly 4 digits.

    Args:
        pinChecked (str): The PIN to be checked."""
        
    if len(pinChecked) != 4 :
        return False
    
    
    pinChecked = str(pinChecked)
    sameNum = 0
    sequentialNum = 0
    
    prevNum = -2
    for x in pinChecked:
        x = int(x)
        if x not in [0,1,2,3,4,5,6,7,8,9]:
            return False
        
        if x == prevNum + 1 or x == prevNum -1:
            sequentialNum += 1
        else:
            sequentialNum = 0
            
        if x == prevNum:
            sameNum += 1
        else:
            sameNum = 0
            
        if sameNum == 3 or sequentialNum == 4:
            return False
        
        prevNum = x
        
    return True
        
        
print(checkPin("4444")) #ok
# - Must be 4 characters in length.
# - Must contain only digits 0-9.
# - Digit cannot be used three or more times in succession.
#   - 4441 is invalid
#   - 4404 is valid
# - PINs cannot be uniformly increasing or decreasing by 1
#   - 1234 is invalid
#   - 9876 is invalid
#   - 1357 is valid
#   - 1232 is valid

print(checkPin("4424")) #ok
print(checkPin("4321"))
print(checkPin("1232"))