code: func (q *Query) Filter(filterString string, value interface{}) *Query {
  	q.query.Filter(filterString, value)
  	return q
  }
docs: // Filter applies a filter to the query, which will cause the query to only
  // return models with field values matching the expression. filterString should
  // be an expression which includes a fieldName, a space, and an operator in that
  // order. For example: Filter("Age >=", 30) would only return models which have
  // an Age value greater than or equal to 30. Operators must be one of "=", "!=",
  // ">", "<", ">=", or "<=". You can only use Filter on fields which are indexed,
  // i.e. those which have the `zoom:"index"` struct tag. If multiple filters are
  // applied to the same query, the query will only return models which have
  // matches for *all* of the filters. Filter will set an error on the query if
  // the arguments are improperly formated, if the field you are attempting to
  // filter is not indexed, or if the type of value does not match the type of the
  // field. The error, same as any other error that occurs during the lifetime of
  // the query, is not returned until the query is executed.