code: def parse_arg(arg):
      
      # handle string input
      if type(arg) == str:
          arg = arg.strip()
          # parse csv as tickers and create children
          if ',' in arg:
              arg = arg.split(',')
              arg = [x.strip() for x in arg]
          # assume single string - create single item list
          else:
              arg = [arg]
  
      return arg
docs: Parses arguments for convenience. Argument can be a
      csv list ('a,b,c'), a string, a list, a tuple.
  
      Returns a list.