identify-device.page.ts

@Component({
  selector: 'app-identify-device',
  template: `
    ...
    <form (submit)="identifyDevice()" [formGroup]="formGroup">
      <ion-item>
        <ion-label color="dark" [position]="'stacked'">Track Number</ion-label>
        <ion-input clearInput type="text" formControlName="trackNumber"></ion-input>
      </ion-item>
    </form>
    ...
  `
})
export class IdentifyDevicePage implements OnInit {

  public formGroup: FormGroup;

  constructor(private _fb: FormBuilder, private _facade: CoreFacade) {
    this.formGroup = this._fb.group({
      trackNumber: ['', [Validators.required]]
    });
  }

  public ngOnInit(): void {
    this.formGroup.controls['trackNumber'].patchValue(this._facade.getTrackNumber());
  }
  
  public identifyDevice(): void {
    this._facade.identifyDevice(this.mh.fcValue('trackNumber'))
      .subscribe(success => success && this._router.navigateByUrl('device-identified'));
  }  
}

What is this.mh.fcValue('trackNumber') ?