[Python] Groupby and Aggregate based on condition

My input data:

df=pd.DataFrame({'ID':['A','B','C','D'],
'Group':['group1','group1','group2','group2'],
'Flag_1':[1,0,0,1],
'Flag_2':[1,1,0,1],
'Value':[30,40,60,70]
})



I am trying to add up "Value" per group when flag is equal to 1. My expected output is:

df_value_group=pd.DataFrame({
'Flag_1 Sum':[1,1],
'Flag_2 Sum':[2,1],
'Value_1 Sum':[30,70],
'Value_2 Sum':[70,70]},
index=['group1','group2'])



I have tried this but it throws me an AssertionError error primarly due to the latter two lambda function.

df.groupby('Group').agg(
**{ 'Flag_1 Sum': ('Flag_1','sum'),
'Flag_2 Sum': ('Flag_2','sum'),
'Value_1 Sum': ('Flag_1', lambda col: df.loc[col.eq(1), 'Value'].sum()),
'Value_2 Sum': ('Flag_2', lambda col: df.loc[col.eq(1), 'Value'].sum())
})

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