@Nullable
      private static PsiAssignmentExpression extractAssignment(@NotNull PsiStatement last) {
        PsiExpressionStatement expressionStatement = tryCast(last, PsiExpressionStatement.class);
        if (expressionStatement == null) return null;
        PsiAssignmentExpression assignment = tryCast(expressionStatement.getExpression(), PsiAssignmentExpression.class);
        if (assignment == null) return null;
        return assignment;
      }
@Nullable
      private static PsiAssignmentExpression extractAssignment(@NotNull PsiStatement last)