YAML file: a.yml
  YAML document
    YAML mapping
      YAML key value
        PsiElement(scalar key)('name')
        PsiElement(:)(':')
        PsiWhiteSpace(' ')
        YAML plain scalar text
          PsiElement(text)('Mark McGwire')
      PsiElement(Eol)('\n')
      YAML key value
        PsiElement(scalar key)('accomplishment')
        PsiElement(:)(':')
        PsiWhiteSpace(' ')
        YAML scalar text
          PsiElement(scalar text)('>')
          PsiElement(block scalar EOL)('\n')
          PsiElement(indent)('  ')
          PsiElement(scalar text)('Mark set a major league')
          PsiElement(block scalar EOL)('\n')
          PsiElement(indent)('  ')
          PsiElement(scalar text)('home run record in 1998.')
      PsiElement(Eol)('\n')
      YAML key value
        PsiElement(scalar key)('stats')
        PsiElement(:)(':')
        PsiWhiteSpace(' ')
        YAML scalar list
          PsiElement(scalar list)('|')
          PsiElement(block scalar EOL)('\n')
          PsiElement(indent)('  ')
          PsiElement(scalar list)('65 Home Runs')
          PsiElement(block scalar EOL)('\n')
          PsiElement(indent)('  ')
          PsiElement(scalar list)('0.278 Batting Average')