text: Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
  ### Context:
  CREATE TABLE Documents (Id VARCHAR); CREATE TABLE Ref_Shipping_Agents (Id VARCHAR)
  ### Question:
  How many documents were shipped by USPS?
  ### Answer:
  SELECT COUNT(*) FROM Ref_Shipping_Agents JOIN Documents ON Documents.shipping_agent_code = Ref_Shipping_Agents.shipping_agent_code WHERE Ref_Shipping_Agents.shipping_agent_name = "USPS"