#Validation
##is digit?
###description
checking the string contains only digits
###example
12345(O), 09876(O), -135(X), +246(X), 36.63(X)
##is alpha?
###description
checking the string contains only alphabetic characters
returns the IP address of the client that called the API.
###caution
For test requests called from https://rapidapi.com/ACSTRGE/api/useful-funcs/endpoints , It is not the clientโs IP address.
Probably the RapidAPI IP address.