type:      seq
sequence:
  -
    type:      map
    mapping:
      name:
        type:       str
        required:   yes
      email:
        type:       str
        required:   yes
        pattern:    /@/
      password:
        type:       text
        length:     { max: 16, min: 8 }
      age:
        type:       int
        range:      { max: 30, min: 18 }
        # or assert: 18 <= val && val <= 30
      blood:
        type:       str
        enum:
          - A
          - B
          - O
          - AB
      birth:
        type:       date
      memo:
        type:       any