------
## 最终结论
```python
def histogram(test):
    """Given a string representing a space separated lowercase letters, return a dictionary
    of the letter with the most repetition and containing the corresponding count.
    If several letters have the same occurrence, return all of them."""
    
    # Step 1: Parse the input string
    letters = test.split()
    
    # Step 2: Count occurrences of each letter
    count_dict = {}
    for letter in letters:
        if letter in count_dict:
            count_dict[letter] += 1
        else:
            count_dict[letter] = 1
            
    # Step 3: Find the maximum occurrence count
    max_count = max(count_dict.values(), default=0)
    
    # Step 4: Filter letters with maximum occurrence
    result = {letter: count for letter, count in count_dict.items() if count == max_count}
    
    return result
```