question: public StrBuilder insert ( int index , boolean value ) { validateIndex ( index ) ; if ( value ) { ensureCapacity ( size + 4 ) ; System . arraycopy ( buffer , index , buffer , index + 4 , size - index ) ; buffer [ index ++ ] = 't' ; buffer [ index ++ ] = 'r' ; buffer [ index ++ ] = 'u' ; buffer [ index ] = 'e' ; size += 4 ; } else { ensureCapacity ( size + 5 ) ; System . arraycopy ( buffer , index , buffer , index + 5 , size - index ) ; buffer [ index ++ ] = 'f' ; buffer [ index ++ ] = 'a' ; buffer [ index ++ ] = 'l' ; buffer [ index ++ ] = 's' ; buffer [ index ] = 'e' ; size += 5 ; } return this ; }
target:  Inserts the value into this builder.