验证NPK读数合法性与单位换算

def solve():
    from pyodide.http import open_url
    from io import StringIO
    import pandas as pd
    st_csv = open_url(____).read()
    st = pd.read_csv(StringIO(____))
    npk_ranges = {r['____']:(____) for _,r in st[st['____'].isin(____)].iterrows()}
    def validate_npk(____):
        errors = []
        for metric in ['____','____','____']:
            val = readings_dict.get(____)
            if val is None: continue
            lo, hi = npk_ranges.get(metric,(____,____))
            if not (____):
                errors.append(metric+"____"+str(____)+"____")
        return errors
    def mg_kg_to_ppm(____):
        return value
    test_readings = [
        {'____':____,'____':____,'____':____},
        {'____':____,'____':____,'____':____},
        {'____':____,'____':____,'____':____},
    ]
    for readings in test_readings:
        errs = validate_npk(____)
        print("____"+str(____)+"____"+("____" if not errs else "____"+str(____)))
    print("____"+str(mg_kg_to_ppm(____))+"____")