Write a python function called validatecreditcard that takes 8-digit credit card number as the input parameter (string value) and display whether that number is valid or not. for example,

validatecreditcard("43589795") will display "valid credit card number"
validatecreditcard("43589795") will display "invalid credit card number"

def validateCreditCard(x):

      if type(x)==str and len(x) == 8:

           print("Valid credit card number")

      else:

          print("Invalid credit card number")

validateCreditCard("43589795")

Explanation:

Run the code on your text editor(vs code, sublime, pycharm ) you will get your desired response. If your input is not of type string and not up to 8 digit you will get the response "invalid credit card number" but if it is of type string and up to 8 digit you will get "Valid credit card number".

But remember python works with indentation so when you are transferring this code to your text editor it will run properly well.

I defined the code using the conventional pattern "def"

After defining the function you create a brackets (x) to accommodate your argument x and end it with a semi colon.  

Then i use "if" statement to make sure only string argument and 8 digit value will be accepted to print a "valid credit card". if your argument does not pass the if statement condition it will print out the else statement condition which is "Invalid credit card number"

Finally, you have to call your function and test various values.

answer(d) sequencing and iteration;