code: def _set_available_styles(self):
          
          options_tagstyle = {'keys': ['param', 'type', 'returns', 'return', 'rtype', 'raise'],
                              'styles': {'javadoc': ('@', ':'),  # tuple:  key prefix, separator
                                         'reST': (':', ':'),
                                         'cstyle': ('\\', ' ')}
                             }
          self.tagstyles = list(options_tagstyle['styles'].keys())
          for op in options_tagstyle['keys']:
              self.opt[op] = {}
              for style in options_tagstyle['styles']:
                  self.opt[op][style] = {'name': options_tagstyle['styles'][style][0] + op,
                                         'sep': options_tagstyle['styles'][style][1]
                                        }
          self.opt['return']['reST']['name'] = ':returns'
          self.opt['raise']['reST']['name'] = ':raises'
          self.groups = {
                      'param': ['params', 'args', 'parameters', 'arguments'],
                      'return': ['returns', 'return'],
                      'raise': ['raises', 'exceptions', 'raise', 'exception']
                      }
docs: Set the internal styles list and available options in a structure as following:
  
              param: javadoc: name = '@param'
                              sep  = ':'
                     reST:    name = ':param'
                              sep  = ':'
                     ...
              type:  javadoc: name = '@type'
                              sep  = ':'
                     ...
              ...
  
          And sets the internal groups style:
              param:  'params', 'args', 'parameters', 'arguments'
              return: 'returns', 'return'
              raise:  'raises', 'raise', 'exceptions', 'exception'