SHELL_SCRIPT
  COMMANDS_LIST
    COMMAND_SUBSTITUTION_COMMAND
      PsiElement(OPEN_BACKQUOTE)('`')
      PsiElement(CLOSE_BACKQUOTE)('`')
  PsiElement(\n)('\n')
  COMMANDS_LIST
    COMMAND_SUBSTITUTION_COMMAND
      PsiElement(OPEN_BACKQUOTE)('`')
      COMPOUND_LIST
        GENERIC_COMMAND_DIRECTIVE
          LITERAL
            PsiElement(word)('echo')
      PsiElement(CLOSE_BACKQUOTE)('`')
  PsiElement(\n)('\n')
  COMMANDS_LIST
    COMMAND_SUBSTITUTION_COMMAND
      PsiElement(OPEN_BACKQUOTE)('`')
      COMPOUND_LIST
        GENERIC_COMMAND_DIRECTIVE
          VARIABLE
            PsiElement(var)('$a')
      PsiElement(CLOSE_BACKQUOTE)('`')
  PsiElement(\n)('\n')
  COMMANDS_LIST
    COMMAND_SUBSTITUTION_COMMAND
      PsiElement(OPEN_BACKQUOTE)('`')
      COMPOUND_LIST
        GENERIC_COMMAND_DIRECTIVE
          PsiElement($)('$')
          ARITHMETIC_EXPANSION
            PsiElement(()('(')
            PsiElement(()('(')
            LITERAL_EXPRESSION
              NUMBER
                PsiElement(int)('123')
            PsiElement())(')')
            PsiElement())(')')
      PsiElement(CLOSE_BACKQUOTE)('`')
  PsiElement(\n)('\n')
  COMMANDS_LIST
    COMMAND_SUBSTITUTION_COMMAND
      PsiElement(OPEN_BACKQUOTE)('`')
      COMPOUND_LIST
        GENERIC_COMMAND_DIRECTIVE
          OLD_ARITHMETIC_EXPANSION
            PsiElement(ARITH_SQUARE_LEFT)('$[')
            LITERAL_EXPRESSION
              NUMBER
                PsiElement(int)('123')
            PsiElement(ARITH_SQUARE_RIGHT)(']')
      PsiElement(CLOSE_BACKQUOTE)('`')