code: def loadCoeffs(filename):
      
      gh = []
      gh2arr = []
      with open(filename) as f:
          text = f.readlines()
          for a in text:
              if a[:2] == 'g ' or a[:2] == 'h ':
                  b = a.split()[3:]
                  b = [float(x) for x in b]
                  gh2arr.append(b)
          gh2arr = np.array(gh2arr).transpose()
          N = len(gh2arr)
          for i in range(N):
              if i < 19:
                  for j in range(120):
                      gh.append(gh2arr[i][j])
              else:
                  for p in gh2arr[i]:
                      gh.append(p)
          gh.append(0)
          return gh
docs: load igrf12 coeffs from file
      :param filename: file which save coeffs (str)
      :return: g and h list one by one (list(float))