Write a function named `negative_sum`

that accepts a string as a parameter representing a file name, which reads input from that file containing a series of integers, and determine whether the sum starting from the first number is ever negative.
The function should pra message indicating whether a negative sum is possible and should return `True`

if a negative sum can be reached and `False`

if not.
For example, if the file contains the following text, your function will consider the sum of just one number (38), the sum of the first two numbers (38 + 4), the sum of the first three numbers (38 + 4 + 19), and so on up to the sum of all of the numbers:

38 4 19 -27 -15 -3 4 19 38

None of these sums is negative, so the function would produce the following message and return `False`

:

no negative sum

If the file instead contains the following numbers, the function finds that a negative sum of -8 is reached after adding 6 numbers together (14 + 7 + -10 + 9 + -18 + -10):

14 7 -10 9 -18 -10 17 42 98

It should output the following and return `True`

, indicating that a negative sum can be reached:

-8 after 6 steps