code: def _build_query(field_name, field_value, operator='__eq__'):
      
      qelem = where(field_name)
  
      if not hasattr(qelem, operator):
          raise NotImplementedError('Operator `{}` not found in query object.'.format(operator))
      else:
          query = getattr(qelem, operator)
  
      return query(field_value)
docs: Create a tinyDB Query object with the format:
      (where(`field_name`) `operator` `field_value`)
  
      Parameters
      ----------
      field_name: str
          The name of the field to be queried.
  
      field_value:
          The value of the field
  
      operator: str
          The comparison operator.
          Check TinyDB.Query class for possible choices.
  
      Returns
      -------
      query: tinydb.database.Query