YAML file: a.yml
  YAML document
    YAML sequence
      YAML sequence item
        PsiElement(-)('-')
        PsiWhiteSpace(' ')
        YAML mapping
          PsiElement(tag)('!qualified.class.name')
          PsiElement(Eol)('\n')
          PsiElement(indent)('    ')
          YAML key value
            PsiElement(scalar key)('propertyOne')
            PsiElement(:)(':')
            PsiWhiteSpace(' ')
            YAML plain scalar text
              PsiElement(text)('bla bla')
          PsiElement(Eol)('\n')
          PsiElement(indent)('    ')
          YAML key value
            PsiElement(scalar key)('propertyWithOneSequence')
            PsiElement(:)(':')
            PsiElement(Eol)('\n')
            PsiElement(indent)('        ')
            YAML sequence
              YAML sequence item
                PsiElement(-)('-')
                PsiWhiteSpace(' ')
                YAML plain scalar text
                  PsiElement(text)('first value')
          PsiElement(Eol)('\n')
          PsiElement(indent)('    ')
          YAML key value
            PsiElement(scalar key)('nextPropertyWithOneSequence')
            PsiElement(:)(':')
            PsiElement(Eol)('\n')
            PsiElement(indent)('        ')
            YAML sequence
              YAML sequence item
                PsiElement(-)('-')
                PsiWhiteSpace(' ')
                YAML plain scalar text
                  PsiElement(text)('first value of another sequence')