Pull all the documents of a doctype

How do I list all documents of a doctype. Tried this code : frappe.get_doc(‘Customer’)
but doesn’t seem to work. I think the name is required. But I don’t need a specific document. How do I list all of it?

General usage: frappe.get_all(doctype, filters, fields) or frappe.get_list(doctype, filters, fields, order_by)

In your specific case: frappe.get_all('Customer')

Checkout the Developer-Cheatsheet for further information.