I used the blow code, and it is running successfully. However, when I try to submit my answer i get an error stating **" Please keep in mind the edge case"** - what does this mean? help please.

def compound_interest(principle,rate,years):

r_rate=float(rate)

y_years=int(years)

i_interest=0

if principle<=0 or rate<=0 or years<=0:

print(i_interest)

else:

for i in range(1,y_years+1):

interest=(principle*r_rate*1)/100

principle = principle + interest

i_interest=interest+i_interest

return i_interest

I AM referring to Pythn Foundations courde , module 48 - http://disq.us/p/27y7jrs