code: def vec2sky(cls, vec, degrees=False):
          
          theta, phi = hp.vec2ang(vec)
          ra = phi
          dec = np.pi/2-theta
  
          if degrees:
              ra = np.degrees(ra)
              dec = np.degrees(dec)
          return cls.radec2sky(ra, dec)
docs: Convert [x,y,z] vectors into sky coordinates ra,dec
  
          Parameters
          ----------
          vec : numpy.array
              Unit vectors as an array of (x,y,z)
  
          degrees
  
          Returns
          -------
          sky : numpy.array
              Sky coordinates as an array of (ra,dec)
  
          See Also
          --------
          :func:`AegeanTools.regions.Region.sky2vec`