code: function deleteTerms( termMap, existingTerms, callback ) {
  			if ( this.verbose ) {
  				this.log( "Deleting old terms..." );
  			}
  
  			async.map( Object.keys( existingTerms ), function( taxonomy, callback ) {
  				var terms = existingTerms[ taxonomy ];
  				this.forEach( Object.keys( terms ), function( term, callback ) {
  					this.deleteTerm( terms[ term ], callback );
  				}, callback );
  			}.bind( this ), function( error ) {
  				if ( error ) {
  					return callback( error );
  				}
  
  				if ( this.verbose ) {
  					this.log( "Deleted all old terms." );
  				}
  
  				callback( null, termMap );
  			}.bind( this ));
  		}
docs: TODO: Don't delete terms until after processing posts. This will allow us to use keywords without defining all of them upfront.