Lenses.scala

//...boilerplate

case class Role(policies: Option[Seq[Policy]]))
case class Policy(statements: Option[Seq[Statement]])
case class Statement(action: String)

val role: Role = ....

/* How do I:
 * Set Role.policies to an empty Seq iff it's None
 * Get the first Policy in Role.policies, adding a new empty Policy if Role.policies is empty
 * Set Policy.statements to an empty Seq iff it's None
 * Append a new Statement to Policy.statements 
 */