how to check if a string contains letters only in python code example

Example: python if string contains char

myString = "<text contains this>"
myOtherString = "AnotherString"

# Casting to string is not needed but it's good practice
# to check for errors 

if str(myString) in str(myOtherString): 
    # Do Something
else:
	# myOtherString didn't contain myString