Update DOCS.md (#849)

Fixed a typo.

DOCS.md

@@ -1006,7 +1006,7 @@ Coconut also allows a single `?` before attribute access, function calling, part
 
 When using a `None`-aware operator for member access, either for a method or an attribute, the syntax is `obj?.method()` or `obj?.attr` respectively. `obj?.attr` is equivalent to `obj.attr if obj is not None else obj`. This does not prevent an `AttributeError` if `attr` is not an attribute or method of `obj`.
 
-The `None`-aware indexing operator is used identically to normal indexing, using `?[]` instead of `[]`. `seq?[index]` is equivalent to the expression `seq[index] is seq is not None else seq`. Using this operator will not prevent an `IndexError` if `index` is outside the bounds of `seq`.
+The `None`-aware indexing operator is used identically to normal indexing, using `?[]` instead of `[]`. `seq?[index]` is equivalent to the expression `seq[index] if seq is not None else seq`. Using this operator will not prevent an `IndexError` if `index` is outside the bounds of `seq`.
 
 Coconut also supports None-aware [pipe operators](#pipes) and [function composition pipes](#function-composition).