SOURCE_FILE
  TRAIT
    TRAIT_KW "trait"
    WHITESPACE " "
    NAME
      IDENT "T"
    WHITESPACE " "
    ASSOC_ITEM_LIST
      L_CURLY "{"
      WHITESPACE " "
      FN
        FN_KW "fn"
        WHITESPACE " "
        NAME
          IDENT "foo"
        PARAM_LIST
          L_PAREN "("
          R_PAREN ")"
        SEMICOLON ";"
      WHITESPACE " "
      R_CURLY "}"
  WHITESPACE "\n"
