def question_input (user_decision=None):
    """Obtains input from user on whether they want to scan barcodes or not.
    
    Parameters
    ----------
    user_decision: default is None, if passed in, will not ask user for input. string type.
     
    Returns
    -------
    True if user input was 'yes'
    False is user input was anything else
    """ 
    # Ask user if they would like to scan a barcode, and obtain their input
    if user_decision == None:
        decision = input("Would you like to scan a barcode? Type 'yes' to begin.  ")
    else:
        decision = user_decision
    
    # Return boolean value based on user response
    if decision == 'yes':
        return True
    else:
        return False