การใช้ operation แบบกำหนดเองกับแต่ละ geometry

# Define a function that returns the closest national park
def closest_national_park(geom, national_parks):
    dist = ____
    idx = ____
    closest_park = ____
    return closest_park

# Call the function on single_mine
print(closest_national_park(____, ____))

# Apply the function to all mining sites
mining_sites['closest_park'] = mining_sites.geometry.____(____, ____=____)
print(mining_sites.head())