merge-anchor.yaml

foo: &foo
  a: foo_a
  thing: foo_thing
  c: foo_c

bar: &bar
  b: bar_b
  thing: bar_thing
  c: bar_c

foobarList:
  b: foobarList_b
  <<: [*foo,*bar]
  c: foobarList_c

foobar:
  c: foobar_c
  <<: *foo
  thing: foobar_thing