pschanely

def dfs(graph: dict[int, list[int]], curr_node: int, visited: list[bool]) -> None:
    """
    Depth First Search (DFS) traversal on a graph.

    This function marks all nodes reachable from `curr_node` as visited.

    :param graph: A dictionary representing the graph, where each key is a node
                  and each value is a list of adjacent nodes. For example:
                  {
                      1: [2, 3],

pschanely

from typing import List

def average(numbers: List[float]) -> float:
    '''
    pre: len(numbers) >= 0
    post: min(numbers) <= __return__ <= max(numbers)
    '''
    return sum(numbers) / len(numbers)

pschanely

from typing import List

def average(numbers: List[float]) -> float:
    '''
    pre: len(numbers) >= 0
    post: min(numbers) <= __return__ <= max(numbers)
    '''
    return sum(numbers) / len(numbers)

pschanely

from dataclasses import dataclass

class HasConsistentHash:
    '''
    A mixin to enforce that classes have hash methods that are consistent
    with thier equality checks.
    '''
    def __eq__(self, other: object) -> bool:
        '''
        post: implies(__return__, hash(self) == hash(other))

pschanely

import time

def age() -> int:
    '''
    post: __return__ >= 0
    '''
    return int(time.time())

pschanely

import re
from typing import Optional

def parse_year(yearstring: str) -> Optional[int]:
    '''
    Something is wrong with this year parser! Can you guess what it is?
    
    post: __return__ is None or 1000 <= __return__ <= 9999
    '''
    return int(yearstring) if re.match('[1-9][0-9][0-9][0-9]', yearstring) else None

pschanely

from typing import List

def binary_search2(a_list: List[int], search_item: int, low: int, high: int, initial_low=None, initial_high=None) -> int:
    """Binary search using recursion with formal verification conditions."""

    # Set initial bounds only on the first call
    if initial_low is None or initial_high is None:
        initial_low, initial_high = low, high

    # Preconditions

pschanely

import re
from typing import Optional

def parse_year(yearstring: str) -> Optional[int]:
    '''
    Something is wrong with this year parser! Can you guess what it is?
    
    post: __return__ is None or 1000 <= __return__ <= 9999
    '''
    return int(yearstring) if re.match('[1-9][0-9][0-9][0-9]', yearstring) else None

pschanely

from typing import List

def average(numbers: List[float]) -> float:
    '''
    pre: len(numbers) >= 0
    post: min(numbers) <= __return__ <= max(numbers)
    '''
    return sum(numbers) / len(numbers)

pschanely

from typing import List

def average(numbers: List[float]) -> float:
    '''
    pre: len(numbers) >= 0
    post: min(numbers) <= __return__ <= max(numbers)
    '''
    if len(numbers) == 0:
        return None