Nested for loops with numbers

[smbx33]

.....
for copy in range(copies):
     ......

Since there's a standard module named copy, the variable with the same name may overshadow it(slim chance, but still). Names that may overshadow standard functions and modules are not recommended. 

How would you know which are? Single word that may sound like a standard function, e,g, map, filter, string. Rule of the thumb - when in doubt, add underscore at the end. Or use the beloved   Pythonic snake style

for copy_ in range(copies):

would be correct then? thanks.