func TEXT(name string, a attr.Attribute, signature string) {
	ctx.Function(name)
	ctx.Attributes(a)
	ctx.SignatureExpr(signature)
}
TEXT starts building a new function called name, with attributes a, and sets its signature (see SignatureExpr).
package build
import (
	"flag"
	"os"
	"github.com/mmcloughlin/avo/attr"
	"github.com/mmcloughlin/avo/buildtags"
	"github.com/mmcloughlin/avo/gotypes"
	"github.com/mmcloughlin/avo/ir"
	"github.com/mmcloughlin/avo/operand"
	"github.com/mmcloughlin/avo/reg"
)
var ctx = NewContext()