def expr_query(criterion)
      selection(criterion) do |selector, field, value|
        selector.merge!(field.__expr_part__(value.__expand_complex__, negating?))
      end
    end
def expr_query(criterion)
      selection(criterion) do |selector, field, value|
        selector.merge!(field.__expr_part__(value.__expand_complex__, negating?))
      end
    end
Create the standard expression query.

 @api private

 @example Create the selection.
   selectable.expr_query(age: 50)

 @param [ Hash ] criterion The field/value pairs.

 @return [ Selectable ] The cloned selectable.

 @since 1.0.0