#poly_diff.py, exercise 6.11

def poly_diff(p):
    dp = {}
    for j in p:
        if j != 0:
            dp[j-1] = j*p[j]
    return dp


#p = 1 + x +x**2
p = {0:1,1:1,2:1}

#expect 1 + 2*x; {0:1,1:2}
print(poly_diff(p))

"""
Terminal> python poly_diff.py
{0: 1, 1: 2}
"""