================================================================================
Simple expression list
================================================================================
a, b
--------------------------------------------------------------------------------

(source_file
  (simple_statement
    (expression_list
      (reference_expression
        (identifier))
      (reference_expression
        (identifier)))))

================================================================================
Expression list inside if
================================================================================
if s.no_inner {
    return '!'
}
--------------------------------------------------------------------------------

(ERROR
  (expression_list
    (type_initializer
      (plain_type
        (qualified_type
          (reference_expression
            (identifier))
          (type_reference_expression
            (identifier))))
      (type_initializer_body
        (short_element_list
          (element
            (reference_expression
              (identifier)))
          (element
            (literal
              (interpreted_string_literal))))))))
