Slicable module for splitting ops into n children ops

If a write operation is too large to send, I'll want to split it into multiple children operations to be sent individually instead. This module can be included in an operation and it splits an array element of the spec between the children ops.
Is this really necessary? We're the only ones implementing this module internally, so I don't think having a specific exception, or an exception at all (outside of the `NoMethodError` it would get) is needed since no developer should be using this and won't need a nice exception.