instruction: Write Go code to go by example: string formatting
output: ```dockerfile
  $ go run string-formatting.go
  struct1: {1 2}
  struct2: {x:1 y:2}
  struct3: main.point{x:1, y:2}
  type: main.point
  bool: true
  int: 123
  bin: 1110
  char: !
  hex: 1c8
  float1: 78.900000
  float2: 1.234000e+08
  float3: 1.234000E+08
  str1: "string"
  str2: "\"string\""
  str3: 6865782074686973
  pointer: 0xc0000ba000
  width1: | 12| 345|
  width2: | 1.20| 3.45|
  width3: |1.20 |3.45 |
  width4: | foo| b|
  width5: |foo |b |
  sprintf: a string
  io: an error
  ```