code: def teff(cluster):
      
      b_vs, _ = cluster.stars()
      teffs = []
      for b_v in b_vs:
          b_v -= cluster.eb_v
          if b_v > -0.04:
              x = (14.551 - b_v) / 3.684
          else:
              x = (3.402 - math.sqrt(0.515 + 1.376 * b_v)) / 0.688
  
          teffs.append(math.pow(10, x))
      return teffs
docs: Calculate Teff for main sequence stars ranging from Teff 3500K - 8000K. Use
      [Fe/H] of the cluster, if available.
  
      Returns a list of Teff values.