By changing a single line in the program of Example E8.1, output the 10 most accurately known constants (excluding those set to their values by definition).
Simply change the line
for rec in constants[::-1][:10]:
for rec in constants[constants['rel_unc'] > 0][:10]:
2.64693e-07 ppm: electron g factor = -2.00232 2.69687e-07 ppm: electron mag. mom. to Bohr magneton ratio = -1.00116 3.7956e-06 ppm: electron magn. moment to Bohr magneton ratio = -1.00116 4.96096e-06 ppm: atomic unit of time = 2.41888e-17 s ...
The most accurately known constant is the electron $g$-factor.