Code Example Customer Model in Magento 2

Customer.php

<?php

    /**
     * Authenticate customer
     *
     * @param  string $login
     * @param  string $password
     * @return bool
     * @throws \Magento\Framework\Exception\LocalizedException
     * Use \Magento\Customer\Api\AccountManagementInterface::authenticate
     */
    public function authenticate($login, $password)
    {
        $this->loadByEmail($login);
        if ($this->getConfirmation() && $this->isConfirmationRequired()) {
            throw new EmailNotConfirmedException(
                __('This account is not confirmed.')
            );
        }
        if (!$this->validatePassword($password)) {
            throw new InvalidEmailOrPasswordException(
                __('Invalid login or password.')
            );
        }
        $this->_eventManager->dispatch(
            'customer_customer_authenticated',
            ['model' => $this, 'password' => $password]
        );
        return true;
    }
    /**
     * Load customer by email
     *
     * @param   string $customerEmail
     * @return  $this
     */
    public function loadByEmail($customerEmail)
    {
        $this->_getResource()->loadByEmail($this, $customerEmail);
        return $this;
    }