1. Better handling of minus unary -16-a a-b
2. Better handling of mulitple operator +-
3. Better handling of comparisonoperator
4. debug messages
fix minus when is unary in identifier

Select a Where -beauty-16=levels =>

{'Statement': [<DML 'Select' at 0x2514048>,
               {'Identifier': [<Name 'a' at 0x2514278>]},
               {'Where': [<Keyword 'Where' at 0x2514368>,
                          {'Comparison': [{'Identifier': [<Operator '-' at 0x2514688>,
                                                          <Name 'beauty' at 0x2514778>,
                                                          <Operator '-' at 0x2514f48>,
                                                          <Integer '16' at 0x2514e58>]},
                                          <Comparison '=' at 0x2514ea8>,
                                          {'Identifier': [<Name 'levels' at 0x2514ef8>]}]}]}]}