func Int32(key string, val int32) Field {
	return Field{
		key:        key,
		fieldType:  int32Type,
		numericVal: int64(val),
	}
}
Int32 adds an int32-valued key:value pair to a Span.LogFields() record
package log
import (
	"fmt"
	"math"
)
type fieldType int
const (
	stringType fieldType = iota
	boolType
	intType
	int32Type
	uint32Type
	int64Type
	uint64Type
	float32Type
	float64Type
	errorType
	objectType
	lazyLoggerType
	noopType
)
type Field struct {
	key          string
	fieldType    fieldType
	numericVal   int64
	stringVal    string
	interfaceVal interface{}
}
func String(key, val string) Field {
	return Field{
		key:       key,
		fieldType: stringType,
		stringVal: val,
	}
}
func Bool(key string, val bool) Field {
	var numericVal int64
	if val {
		numericVal = 1
	}
	return Field{
		key:        key,
		fieldType:  boolType,
		numericVal: numericVal,
	}
}
func Int(key string, val int) Field {
	return Field{
		key:        key,
		fieldType:  intType,
		numericVal: int64(val),
	}
}