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Write a Python function `frequency_lists` that takes a list of lists as input and returns a dictionary where the keys are the unique elements from the flattened list, and the values are the counts of their occurrences.
#### Example Usage
```python [main.nopy]
frequency_lists([[1, 2, 3, 2], [4, 5, 6, 2], [7, 8, 9, 5]])
# Output: {1: 1, 2: 3, 3: 1, 4: 1, 5: 2, 6: 1, 7: 1, 8: 1, 9: 1}
frequency_lists([[1, 2], [2, 3], [3, 4]])
# Output: {1: 1, 2: 2, 3: 2, 4: 1}
```
#### Constraints
- The input will always be a list of lists.
- The inner lists can contain integers.
- The function should handle empty lists gracefully.def frequency_lists(list_of_lists):
"""
Calculate the frequency of each element in a flattened list of lists.
Args:
list_of_lists (list of list of int): A list containing sublists of integers.
Returns:
dict: A dictionary with elements as keys and their frequencies as values.
"""
# Flatten the list of lists into a single list
# Count the frequency of each element
# Return the frequency dictionary
pass