Please read this article

1. First of all please see the test files.

2. typical usage

   // create new io.Reader from inputs
   code := strings.NewReader("++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++..+++.>>.<-.<.+++.------.--------.>>+.>++.") //Hello World!\n
   
   // Standards interface to io
   input := new(bytes.Buffer)
   output := new(bytes.Buffer)
   
   // initialize the machine
   bfm := interpreter.NewInterpreter(input, output, code)
   
   // Store the result in output interface 
   err := bfm.Run()
   if err != nil {
       //handle err
   }
   
   // print the result 
   fmt.Println (output.String()) 

3. Add custom operators

   // create new io.Reader from inputs
   code := strings.NewReader("+++***") // (1+1+1)*(2*2*2) = 24
   
   // Standards interface to io
   input := new(bytes.Buffer)
   output := new(bytes.Buffer)
   
   // initialize the machine
   bfm := interpreter.NewInterpreter(input, output, code)
   
   // Add your own operator
   // C is complementary information about instructionlike position or counts of occurrence
   // Incase of opening loop, C is the index of the closing loop and vice versa
   err := bfm.AddOperator('*', func(c int, memory *interpreter.Memory) {
       memory.Cell[memory.Cursor] = (memory.Cell[memory.Cursor] * int(math.Pow(2, float64(c)))) % 255
   })
   
   // Store the result in output interface 
   err := bfm.Run()
   if err != nil {
       //handle err
   }
   
   // print the result of arbitrary cell in the memory
   fmt.Println (bfm.GetValueInMemory(0))

In the root of the project run go test ./...