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Given the following text problem statement, write Python code to implement the functionality described below in problem statement
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Problem:
I would like to aggregate user transactions into lists in pandas. I can't figure out how to make a list comprised of more than one field. For example,
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Python Code:
import pandas as pd
df = pd.DataFrame({'user':[1,1,2,2,3], 'time':[20,10,11,18, 15], 'amount':[10.99, 4.99, 2.99, 1.99, 10.99]})
### Output your answer into variable 'result'
def g(df):
    return df.groupby('user')[['time', 'amount']].apply(lambda x: x.values.tolist()[::-1]).to_frame(name='amount-time-tuple')
result = g(df.copy())
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