error TS2339: Property 'query' does not exist on type 'typeof CoreService'.

import { CoreService} from "./../core.service";

  CoreService.query('login','POST',{username: this.username, password: this.password}).takeUntil(this.ngUnsubscribe).subscribe((value) => {

        });

import { throwError as observableThrowError, interval as observableInterval, Observable,  Subscription , Subject} from 'rxjs';
import { tap, map } from 'rxjs/operators';

import { Injectable } from '@angular/core';
import {  RequestOptions, URLSearchParams } from '@angular/http';
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { environment } from './../environments/environment';
import { Router, NavigationEnd, CanActivate, ActivatedRouteSnapshot, RouterStateSnapshot } from '@angular/router';

@Injectable({providedIn: 'root'})
export class CoreService {
  constructor(private http: HttpClient, private router: Router) {}

  result = {};
  permission = false;
  baseurl = environment.apiUrl;
  baseapi = this.baseurl + ':3000/api';
  options = {withCredentials: true};




  query(action,type,postdata) {

    // console.log("calling: " + type + " : " + action);
    if (type == 'POST') {
      return this.http.post(this.baseapi   + "/" + action, postdata ,this.options).pipe(
          map(result => result),
          tap(result => this.result = result),);



    } else {
      return this.http.get(this.baseapi + "/" + action, this.options).pipe(
          map(result => result),
          tap(result => this.result = result),);
    }

  }




  performLogin(name: string, password: string) {
    var params = new URLSearchParams();
    params.append('username', name);
    params.append('password', password);

    return this.http.post(this.baseapi + '/login/login',params, this.options).pipe(
        map(result => result),
        tap(result => this.result = result),);
  }




}