function get_called_class( $bt = false, $l = 1 ) {
		if ( ! $bt ) {
			$bt = debug_backtrace();
		}
		if ( ! isset ( $bt[ $l ] ) ) {
			throw new Exception ( "Cannot find called class -> stack level too deep." );
		}
		if ( ! isset( $bt[ $l ]['type'] ) ) {
			throw new Exception ( 'type not set' );
		} else switch ( $bt[ $l ]['type'] ) {
			case '::':
				$lines      = file( $bt[ $l ]['file'] );
				$i          = 0;
				$callerLine = '';
				do {
					$i ++;
					$callerLine = $lines[ $bt[ $l ]['line'] - $i ] . $callerLine;
				} while ( stripos( $callerLine, $bt[ $l ]['function'] ) === false );
				preg_match( '/([a-zA-Z0-9\_]+)::' . $bt[ $l ]['function'] . '/', $callerLine, $matches );
				if ( ! isset( $matches[1] ) ) {
					// must be an edge case.
					throw new Exception ( "Could not find caller class: originating method call is obscured." );
				}
				switch ( $matches[1] ) {
					case 'self':
					case 'parent':
						return get_called_class( $bt, $l + 1 );
					default:
						return $matches[1];
				}
			// won't get here.
			case '->':
				switch ( $bt[ $l ]['function'] ) {
					case '__get':
						// edge case -> get class of calling object
						if ( ! is_object( $bt[ $l ]['object'] ) ) {
							throw new Exception ( "Edge case fail. __get called on non object." );
						}

						return get_class( $bt[ $l ]['object'] );
					default:
						return get_class( $bt[ $l ]['object'] );
				}
			default:
				throw new Exception ( "Unknown backtrace method type" );
		}
	}