How to properly send email with sendgrid via php - php

Question

I have the code below which is from sendgrid for sending an email with my API key but I cannot get it to work as it displays
error Fatal error: Uncaught Error: Call to a member function send() on
string in ...
I have install composer as required
It seems, However, $sendgrid->send($email) doesn't actually return anything, so $mail is an empty variable.
Any idea on how to resolve this.
Api link source.
<?php
// https://sendgrid.com/docs/API_Reference/index.html
// using SendGrid's PHP Library
// https://github.com/sendgrid/sendgrid-php
require 'vendor/autoload.php'; // If you're using Composer (recommended)
// Comment out the above line if not using Composer
// require("./sendgrid-php.php");
// If not using Composer, uncomment the above line
$email = new \SendGrid\Mail\Mail();
$email->setFrom("test#example.com", "Example User");
$email->setSubject("Sending with SendGrid is Fun");
$email->addTo("test#example.com", "Example User");
$email->addContent(
"text/plain", "and easy to do anywhere, even with PHP"
);
$email->addContent(
"text/html", "<strong>and easy to do anywhere, even with PHP</strong>"
);
//$sendgrid = new \SendGrid(getenv('my api goes here'));
$sendgrid = 'my api goes here';
try {
$response = $sendgrid->send($email);
print $response->statusCode() . "\n";
print_r($response->headers());
print $response->body() . "\n";
} catch (Exception $e) {
echo 'Caught exception: ', $e->getMessage(), "\n";
}

Answer 1

You are trying to call a function on a string.
$sendgrid = 'my api goes here';
And later:
$response = $sendgrid->send($email);
What I think you meant:
$response = $email->send($email);