code: def _parse(self, params):
          ''' parse parameters and return SQL 
          '''
          if not isinstance(params, dict):
              return None, None
  
          if len(params) == 0:
              return None, None
  
          selectors = list()
          modifiers = list()
          
          for k in params.keys():
  
              if k in LOGICAL_OPERATORS:
                  selectors.append(self._logical(k, params[k]))
  
              elif k in QUERY_MODIFIERS:
                  modifiers.append(self._modifier(k, params[k]))
  
              else:
                  if k == '_id':
                      selectors.append("rowid%s" % (self._value_wrapper(params[k])))
                  else:
                      selectors.append("%s%s" % (k, self._value_wrapper(params[k])))
  
          _selectors = ' AND '.join(selectors).strip()
          _modifiers = ' '.join(modifiers).strip()
          return _selectors, _modifierf _parse(self, params):
          ''' parse parameters and return SQL 
          '''
          if not isinstance(params, dict):
              return None, None
  
          if len(params) == 0:
              return None, None
  
          selectors = list()
          modifiers = list()
          
          for k in params.keys():
  
              if k in LOGICAL_OPERATORS:
                  selectors.append(self._logical(k, params[k]))
  
              elif k in QUERY_MODIFIERS:
                  modifiers.append(self._modifier(k, params[k]))
  
              else:
                  if k == '_id':
                      selectors.append("rowid%s" % (self._value_wrapper(params[k])))
                  else:
                      selectors.append("%s%s" % (k, self._value_wrapper(params[k])))
  
          _selectors = ' AND '.join(selectors).strip()
          _modifiers = ' '.join(modifiers).strip()
          return _selectors, _modifiers
docs: parse parameters and return SQL