func Equal(e1 *snomed.Expression, e2 *snomed.Expression) bool {
	renderer := NewCanonicalRenderer()
	s1, _ := renderer.Render(e1)
	s2, _ := renderer.Render(e2)
	return strings.EqualFold(s1, s2)
}
Equal determines whether two expressions are exactly equal
package expression
import (
	"errors"
	"fmt"
	"strconv"
	"strings"
	"github.com/antlr/antlr4/runtime/Go/antlr"
	"github.com/wardle/go-terminology/expression/cg"
	"github.com/wardle/go-terminology/snomed"
)
func CreateSimpleExpression(concept *snomed.Concept) *snomed.Expression {
	exp := snomed.Expression{}
	clause := &snomed.Expression_Clause{}
	concepts := make([]*snomed.ConceptReference, 0)
	concepts = append(concepts, &snomed.ConceptReference{ConceptId: concept.Id})
	clause.FocusConcepts = concepts
	exp.Clause = clause
	return &exp
}