In [31]: run Exercise04.py
mass of pion = 150.42 +/- 18.7628 MeV/c^2
coupling constant = 62.7632 +/- 9.52932 (MeV fm)^0.5
reduced chi^2 = 0.837342
goodness-of-fit = 0.473121
g2/hbarc = 19.9656 +/- 6.06276
