M0013 no new variables

example $ marmot build .
error[M0013]: no new variables on left side of :=
 --> ./main.go:5:4
  |
5 |     x := 2
  |       ^^ no new variables on the left
  |
help: use `=` instead of `:=`
  |
5 -     x := 2
5 +     x = 2
  |

error: build failed with 1 error
1 error can be fixed automatically: run `marmot fix`
for more about an error, run `marmot explain M0013`

package main

func main() {
	x := 1
	x := 2
	_ = x
}