foo: fooval

bar:
  foo: barfooval

  nested:
    foo:
      bar: nestedfoobarval

sub:
  foo: ${foo} - ${bar.foo}
  bar:
    foo: ${bar.foo}
    nested: ${bar.nested.foo.bar}

sub2:
  foo: ${sub.foo}
  bar:
    foo: ${sub.bar.foo}
    nested: ${sub.bar.nested}

sub3:
  foo: ${sub2.foo}
  bar:
    foo: ${sub2.bar.foo}
    nested: ${sub2.bar.nested}

sub4:
  foo: ${sub3.foo}
  bar:
    foo: ${sub3.bar.foo}

sub5: ${nonexistant.value}
sub6: ${basic.var1}