YAML file: a.yml
  YAML document
    YAML mapping
      YAML key value
        PsiElement(?)('?')
        PsiElement(Eol)('\n')
        PsiElement(indent)('  ')
        YAML sequence
          YAML sequence item
            PsiElement(-)('-')
            PsiWhiteSpace(' ')
            YAML plain scalar text
              PsiElement(text)('Detroit Tigers')
          PsiElement(Eol)('\n')
          PsiElement(indent)('  ')
          YAML sequence item
            PsiElement(-)('-')
            PsiWhiteSpace(' ')
            YAML plain scalar text
              PsiElement(text)('Chicago cubs')
        PsiElement(Eol)('\n')
        PsiElement(:)(':')
        PsiElement(Eol)('\n')
        PsiElement(indent)('  ')
        YAML sequence
          YAML sequence item
            PsiElement(-)('-')
            PsiWhiteSpace(' ')
            YAML plain scalar text
              PsiElement(text)('2001-07-23')
      PsiElement(Eol)('\n')
      PsiElement(Eol)('\n')
      YAML key value
        PsiElement(?)('?')
        PsiWhiteSpace(' ')
        YAML array
          PsiElement([)('[')
          PsiWhiteSpace(' ')
          YAML sequence item
            YAML plain scalar text
              PsiElement(text)('New York Yankees')
          PsiElement(,)(',')
          PsiElement(Eol)('\n')
          PsiElement(indent)('    ')
          YAML sequence item
            YAML plain scalar text
              PsiElement(text)('Atlanta Braves')
          PsiWhiteSpace(' ')
          PsiElement(])(']')
        PsiElement(Eol)('\n')
        PsiElement(:)(':')
        PsiWhiteSpace(' ')
        YAML array
          PsiElement([)('[')
          PsiWhiteSpace(' ')
          YAML sequence item
            YAML plain scalar text
              PsiElement(text)('2001-07-02')
          PsiElement(,)(',')
          PsiWhiteSpace(' ')
          YAML sequence item
            YAML plain scalar text
              PsiElement(text)('2001-08-12')
          PsiElement(,)(',')
          PsiElement(Eol)('\n')
          PsiElement(indent)('    ')
          YAML sequence item
            YAML plain scalar text
              PsiElement(text)('2001-08-14')
          PsiWhiteSpace(' ')
          PsiElement(])(']')