You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: member.go
    path of file: ./repos/coder/coderd/rbac/regosql/sqltypes
    
    the code of the file until where you have to start completion: package sqltypes

import (
	"golang.org/x/xerrors"
)

// SupportsContains is an interface that can be implemented by types that
// support "me.Contains(other)". This is `internal_member2` in the rego.
type SupportsContains interface {
	ContainsSQL(cfg *SQLGenerator, other Node) (string, error)
}

/
    
func (e memberOf) SQLString(cfg *SQLGenerator) string {
	// Equalities can be flipped without changing the result, so we can
	// try both left = right and right = left.
	if sc, ok := e.Haystack.(SupportsContains); ok {
		v, err := sc.ContainsSQL(cfg, e.Needle)
		if err == nil {
			return v
		}
	}

	if sc, ok := e.Needle.(SupportsContainedIn); ok {
		v, err := sc.ContainedInSQL(cfg, e.Haystack)
		if err == nil {
			return v
		}
	}

	cfg.AddError(xerrors.Errorf("unsupported contains: %T contains %T", e.Haystack, e.Needle))
	return "MemberOfError"
}