code: def angles(self) -> Tuple[float]:
          
          m = self._matrix
          lengths = self.lengths
          angles = np.zeros(3)
          for i in range(3):
              j = (i + 1) % 3
              k = (i + 2) % 3
              angles[i] = abs_cap(dot(m[j], m[k]) / (lengths[j] * lengths[k]))
          angles = np.arccos(angles) * 180.0 / pi
          return tuple(angles.tolist())
docs: Returns the angles (alpha, beta, gamma) of the lattice.