code: def Rules(**rules):
      
      for (lhs, rhs) in rules.items():
          rules[lhs] = [alt.strip().split() for alt in rhs.split('|')]
      return rules
docs: Create a dictionary mapping symbols to alternative sequences.
      >>> Rules(A = "B C | D E")
      {'A': [['B', 'C'], ['D', 'E']]}