SOURCE_FILE
  TYPE_ALIAS
    TYPE_KW "type"
    WHITESPACE " "
    NAME
      IDENT "X"
    WHITESPACE " "
    EQ "="
    WHITESPACE " "
    PATH_TYPE
      PATH
        PATH
          PATH_SEGMENT
            L_ANGLE "<"
            PATH_TYPE
              PATH
                PATH_SEGMENT
                  NAME_REF
                    IDENT "A"
            WHITESPACE " "
            AS_KW "as"
            WHITESPACE " "
            PATH_TYPE
              PATH
                PATH_SEGMENT
                  NAME_REF
                    IDENT "B"
            R_ANGLE ">"
        COLON2 "::"
        PATH_SEGMENT
          NAME_REF
            IDENT "Output"
    SEMICOLON ";"
  WHITESPACE "\n"
  FN
    FN_KW "fn"
    WHITESPACE " "
    NAME
      IDENT "foo"
    PARAM_LIST
      L_PAREN "("
      R_PAREN ")"
    WHITESPACE " "
    BLOCK_EXPR
      STMT_LIST
        L_CURLY "{"
        WHITESPACE " "
        EXPR_STMT
          CALL_EXPR
            PATH_EXPR
              PATH
                PATH
                  PATH_SEGMENT
                    L_ANGLE "<"
                    PATH_TYPE
                      PATH
                        PATH_SEGMENT
                          NAME_REF
                            IDENT "usize"
                    WHITESPACE " "
                    AS_KW "as"
                    WHITESPACE " "
                    PATH_TYPE
                      PATH
                        PATH_SEGMENT
                          NAME_REF
                            IDENT "Default"
                    R_ANGLE ">"
                COLON2 "::"
                PATH_SEGMENT
                  NAME_REF
                    IDENT "default"
            ARG_LIST
              L_PAREN "("
              R_PAREN ")"
          SEMICOLON ";"
        WHITESPACE " "
        R_CURLY "}"
  WHITESPACE "\n"