# Dictionary size cant be changed during iteration

```python
#!/usr/bin/python3
def complex_delete(a_dictionary, value):
    for k, v in a_dictionary.items():
        if v == value:
            del a_dictionary[k]
    return a_dictionary
```

When you run something like this(the code above), you will get the following errors

```python
Traceback (most recent call last):
  File "./102-main.py", line 7, in <module>
    new_dict = complex_delete(a_dictionary, 'C')
  File "/root/alx-higher_level_programming/0x04-python-more_data_structures/102-complex_delete.py", line 3, in complex_delete
    for k, v in a_dictionary.items():
RuntimeError: dictionary changed size during iteration
```

why?  
The issue here lies in modifying the dictionary (`a_dictionary`) while iterating over its items. Modifying the dictionary size during iteration can lead to unexpected results or runtime errors. To overcome this, you can create a separate list of keys to delete and then delete them after the iteration is complete. Here's an updated version below:

```python
python
Copy code
def complex_delete(a_dictionary, value):
    keys_to_delete = []
    for k, v in a_dictionary.items():
        if v == value:
            keys_to_delete.append(k)
    for k in keys_to_delete:
        del a_dictionary[k]
    return a_dictionary
```

> **0x04. Python - More Data Structures: Set, Dictionary**  
> 102-complex\_delete.py