YAML file: a.yml
  YAML document
    YAML mapping
      YAML key value
        PsiElement(scalar key)('Stack')
        PsiElement(:)(':')
        PsiElement(Eol)('\n')
        PsiElement(indent)('  ')
        YAML sequence
          YAML sequence item
            PsiElement(-)('-')
            PsiWhiteSpace(' ')
            YAML mapping
              YAML key value
                PsiElement(scalar key)('file')
                PsiElement(:)(':')
                PsiWhiteSpace(' ')
                YAML plain scalar text
                  PsiElement(text)('TopClass.py')
              PsiElement(Eol)('\n')
              PsiElement(indent)('    ')
              YAML key value
                PsiElement(scalar key)('line')
                PsiElement(:)(':')
                PsiWhiteSpace(' ')
                YAML plain scalar text
                  PsiElement(text)('23')
              PsiElement(Eol)('\n')
              PsiElement(indent)('    ')
              YAML key value
                PsiElement(scalar key)('code')
                PsiElement(:)(':')
                PsiWhiteSpace(' ')
                YAML scalar list
                  PsiElement(scalar list)('|')
                  PsiElement(block scalar EOL)('\n')
                  PsiElement(indent)('      ')
                  PsiElement(scalar list)('x = MoreObject("345\n")')
          PsiElement(Eol)('\n')
          PsiElement(indent)('  ')
          YAML sequence item
            PsiElement(-)('-')
            PsiWhiteSpace(' ')
            YAML mapping
              YAML key value
                PsiElement(scalar key)('file')
                PsiElement(:)(':')
                PsiWhiteSpace(' ')
                YAML plain scalar text
                  PsiElement(text)('MoreClass.py')
              PsiElement(Eol)('\n')
              PsiElement(indent)('    ')
              YAML key value
                PsiElement(scalar key)('line')
                PsiElement(:)(':')
                PsiWhiteSpace(' ')
                YAML plain scalar text
                  PsiElement(text)('58')
              PsiElement(Eol)('\n')
              PsiElement(indent)('    ')
              YAML key value
                PsiElement(scalar key)('code')
                PsiElement(:)(':')
                PsiWhiteSpace(' ')
                YAML scalar list
                  PsiElement(scalar list)('|-')
                  PsiElement(block scalar EOL)('\n')
                  PsiElement(indent)('      ')
                  PsiElement(scalar list)('foo = bar')