Rule 107. Rule of Optional Completeness

When part of an act, declaration, conversation, writing or recorded statement is given in evidence by one party, the whole on the same subject may be inquired into by the other, and any other act, declaration, writing or recorded statement which is necessary to make it fully understood or to explain the same may also be given in evidence, as when a letter is read, all letters on the same subject between the same parties may be given. “Writing or recorded statement” includes depositions.