Initialised composer, started prototyping.

src/ClientInterface.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Toloka\PhpApi;
+
+interface ClientInterface {
+
+  /**
+   * Login using credentials.
+   *
+   * @param string $login
+   *
+   * @param string $password
+   *
+   * @throws InvalidAuthCredentials
+   *
+   * @return void
+   */
+  public function login(string $login, string $password): void;
+
+}