SHELL_SCRIPT
  PsiComment(Comment)('#This is an echo command which has four params: empty backquote, echo, a, empty backquote')
  PsiElement(\n)('\n')
  COMMANDS_LIST
    SIMPLE_COMMAND
      GENERIC_COMMAND_DIRECTIVE
        LITERAL
          PsiElement(word)('echo')
      PsiWhiteSpace(' ')
      SIMPLE_COMMAND_ELEMENT
        COMMAND_SUBSTITUTION_COMMAND
          PsiElement(OPEN_BACKQUOTE)('`')
          PsiElement(CLOSE_BACKQUOTE)('`')
      PsiWhiteSpace(' ')
      LITERAL
        PsiElement(word)('echo')
      PsiWhiteSpace(' ')
      LITERAL
        PsiElement(word)('a')
      PsiWhiteSpace(' ')
      SIMPLE_COMMAND_ELEMENT
        COMMAND_SUBSTITUTION_COMMAND
          PsiElement(OPEN_BACKQUOTE)('`')
          PsiElement(CLOSE_BACKQUOTE)('`')