from typing import Optional, Sequence
from simfile.types import Chart

# Imperative version
def get_hardest_chart(charts) -> Optional[Chart]:
    hardest_chart: Optional[Chart] = None
    hardest_meter: Optional[int] = None

    for chart in charts:
        # Remember to convert `meter` to an integer for comparisons
        meter = int(chart.meter or "1")
        if hardest_meter is None or meter > hardest_meter:
            hardest_chart = chart
            hardest_meter = meter

    return hardest_chart


# One-liner version
def get_hardest_chart(charts: Sequence[Chart]) -> Optional[Chart]:
    return max(
        charts,
        key=lambda chart: int(chart.meter or "1"),
        default=None,
    )