code: def rot_from_vectors(start_vec, end_vec):
          
  
          dot = start_vec.dot(end_vec)
          # TODO: check if dot is a valid number
          angle = math.acos(dot)
          # TODO: check if angle is a valid number
          cross = start_vec.cross(end_vec)
          cross.normalize
          rot_matrix = Matrix44.from_axis_angle(cross, angle)
  
          # TODO: catch exception and return identity for invalid numbers
          return rot_matrix
docs: Return the rotation matrix to rotate from one vector to another.