private static void addAdditionalKeys(final PsiFile file, final PsiElement operand, final DictKeyCompletionResultSet result) {
    Collection<PySubscriptionExpression> subscriptionExpressions = PsiTreeUtil.findChildrenOfType(file, PySubscriptionExpression.class);
    for (PySubscriptionExpression expr : subscriptionExpressions) {
      if (expr.getOperand().getText().equals(operand.getText()) &&
          expr.getParent() instanceof PyAssignmentStatement assignmentStatement &&
          expr.equals(assignmentStatement.getLeftHandSideExpression()) &&
          expr.getIndexExpression() instanceof PyStringLiteralExpression key) {
        result.addKey(key);
      }
    }
  }
private static void addAdditionalKeys(final PsiFile file, final PsiElement operand, final DictKeyCompletionResultSet result)