Reuse a block of code in YAML

# sequencer protocols for Laser eye surgery
---
- step:  &id001                  # defines anchor label &id001
    instrument:      Lasik 2000
    pulseEnergy:     5.4
    pulseDuration:   12
    repetition:      1000
    spotSize:        1mm

- step: &id002
    instrument:      Lasik 2000
    pulseEnergy:     5.0
    pulseDuration:   10
    repetition:      500
    spotSize:        2mm

- step: *id001                   # refers to the first step (with anchor &id001)
- step: *id002                   # refers to the second step
- step: *id001
- step: *id002

sample from wikipedia

Try reusing a full group by importing it:

Defaults: &defaults
  Company: foo
  Item: 123

Computer:
  <<: *defaults
  Price: 3000

Documentation: http://yaml.org/type/merge.html