def hash_employee_data(employee_data):
    """
    Hashes employee data by email for quick lookup.  This is
    necessary for efficient comparison of remote and local data.
    Returns
    -------
    Dictionary - employee email to employee_data
    """
    email_to_employee = {}
    for employee in employee_data:
        email_to_employee[employee['email']] = employee
    return email_to_employee