The following incomplete Python function is intended to return the maximum number in a given list of numbers, where the list may contain many nesting levels. 

def RecMax(L): 

     if (type(L) is not list) or (len(L) < 1): 
          return None
     if len(L) == 1:
          if type(L[0]) is list:
             return …………(T)…………
          else:
             return L[0]
     else:
          if type(L[0]) is list:
             return max(…………(U)…………)
          else:
             return max(L[0], RecMax(L[1:]))