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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def connect(host, port, username, password):
 """Connect and login to an FTP server and return ftplib.FTP object."""

        # Instantiate ftplib client
        session = ftplib.FTP()

        # Connect to host without auth
        session.connect(host, port)

        # Authenticate connection
        session.login(username, password)
        return session