from typing import List
def all_prefixes(string: str) -> List[str]:
    result = []
    for i in range(len(string)):
        result.append(string[:i+1])
    return result
from typing import List
def has_close_elements(numbers: List[float], threshold: float) -> bool:
    for idx, elem in enumerate(numbers):
        for idx2, elem2 in enumerate(numbers):
            if idx != idx2:
                distance = abs(elem - elem2)
                if distance < threshold:
                    return True
    return False