How can I find the index of the next not NaN element in a python list

so I have the list:

['string_one', nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, 'string_two', nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, 'string_three', nan, nan, nan, 
nan, nan, nan, nan, nan, nan, nan, nan, 'string_four', nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, "string_five", nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan]

this list is in the def with parametr that equals to one of the strings from the list. I need to find index of the next string

upd:
I am using pandas and nan came from the excel table. I got the right answer, please stop downvote me 😉

>Solution :

There are many ways to do it, here is one of them:

my_list = ['x', None, None, 'y', None] 
for index, elem in enumerate(my_list):
    if elem is not None:
        print(index)