void (@NotNull final CompletionParameters parameters, @NotNull final ProcessingContext context, @NotNull CompletionResultSet result) { final PsiElement original = parameters.getOriginalPosition(); if (original != null) { final PsiElement parent = original.getParent(); result = result.withPrefixMatcher(getPrefix(parameters.getOffset(), parent.getContainingFile())); if (parent instanceof PyStringLiteralExpression) { result.addAllElements(addCompletionsForSubstitutions(parameters, original, (PyStringLiteralExpression)parent)); } } }